diff --git a/gocardless_pro/services/payer_authorisations_service.py b/gocardless_pro/services/payer_authorisations_service.py
index 09db9986..d6ee7672 100644
--- a/gocardless_pro/services/payer_authorisations_service.py
+++ b/gocardless_pro/services/payer_authorisations_service.py
@@ -3,6 +3,8 @@
 #   https://github.com/gocardless/crank
 #
 
+import warnings
+
 from . import base_service
 from .. import resources
 from ..paginator import Paginator
@@ -23,6 +25,9 @@ def get(self,identity,params=None, headers=None):
         Retrieves the details of a single existing Payer Authorisation. It can
         be used for polling the status of a Payer Authorisation.
 
+        Deprecated:
+            Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.
+
         Args:
               identity (string): Unique identifier, beginning with "PA".
               params (dict, optional): Query string parameters.
@@ -30,6 +35,8 @@ def get(self,identity,params=None, headers=None):
         Returns:
               PayerAuthorisation
         """
+        warnings.warn("Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.",
+                      DeprecationWarning, stacklevel=2)
         path = self._sub_url_params('/payer_authorisations/:identity', {
           
             'identity': identity,
@@ -51,12 +58,17 @@ def create(self,params=None, headers=None):
         save any payer data on your servers or the browser while still being
         able to implement a progressive solution, such as a multi-step form.
 
+        Deprecated:
+            Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.
+
         Args:
               params (dict, optional): Request body.
 
         Returns:
               PayerAuthorisation
         """
+        warnings.warn("Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.",
+                      DeprecationWarning, stacklevel=2)
         path = '/payer_authorisations'
         
         if params is not None:
@@ -89,6 +101,9 @@ def update(self,identity,params=None, headers=None):
         update the `metadata` attribute values it must be sent completely as it
         overrides the previously existing values. 
 
+        Deprecated:
+            Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.
+
         Args:
               identity (string): Unique identifier, beginning with "PA".
               params (dict, optional): Request body.
@@ -96,6 +111,8 @@ def update(self,identity,params=None, headers=None):
         Returns:
               PayerAuthorisation
         """
+        warnings.warn("Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.",
+                      DeprecationWarning, stacklevel=2)
         path = self._sub_url_params('/payer_authorisations/:identity', {
           
             'identity': identity,
@@ -118,6 +135,9 @@ def submit(self,identity,params=None, headers=None):
         it is successfully submitted, the Payer Authorisation can no longer be
         edited.
 
+        Deprecated:
+            Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.
+
         Args:
               identity (string): Unique identifier, beginning with "PA".
               params (dict, optional): Request body.
@@ -125,6 +145,8 @@ def submit(self,identity,params=None, headers=None):
         Returns:
               PayerAuthorisation
         """
+        warnings.warn("Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.",
+                      DeprecationWarning, stacklevel=2)
         path = self._sub_url_params('/payer_authorisations/:identity/actions/submit', {
           
             'identity': identity,
@@ -151,6 +173,9 @@ def confirm(self,identity,params=None, headers=None):
         they go through our flow or make them go through the necessary
         verification mechanism (upcoming feature).
 
+        Deprecated:
+            Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.
+
         Args:
               identity (string): Unique identifier, beginning with "PA".
               params (dict, optional): Request body.
@@ -158,6 +183,8 @@ def confirm(self,identity,params=None, headers=None):
         Returns:
               PayerAuthorisation
         """
+        warnings.warn("Payer Authorisation is legacy API and cannot be used by new integrators. The Billing Request (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for any new integrations.",
+                      DeprecationWarning, stacklevel=2)
         path = self._sub_url_params('/payer_authorisations/:identity/actions/confirm', {
           
             'identity': identity,
diff --git a/gocardless_pro/services/redirect_flows_service.py b/gocardless_pro/services/redirect_flows_service.py
index d2d8f269..f467f4b0 100644
--- a/gocardless_pro/services/redirect_flows_service.py
+++ b/gocardless_pro/services/redirect_flows_service.py
@@ -3,6 +3,8 @@
 #   https://github.com/gocardless/crank
 #
 
+import warnings
+
 from . import base_service
 from .. import resources
 from ..paginator import Paginator
@@ -23,12 +25,17 @@ def create(self,params=None, headers=None):
         Creates a redirect flow object which can then be used to redirect your
         customer to the GoCardless hosted payment pages.
 
+        Deprecated:
+            Redirect Flows are legacy APIs and cannot be used by new integrators. The Billing Request flow (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for your payment flows.
+
         Args:
               params (dict, optional): Request body.
 
         Returns:
               RedirectFlow
         """
+        warnings.warn("Redirect Flows are legacy APIs and cannot be used by new integrators. The Billing Request flow (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for your payment flows.",
+                      DeprecationWarning, stacklevel=2)
         path = '/redirect_flows'
         
         if params is not None:
@@ -53,6 +60,9 @@ def get(self,identity,params=None, headers=None):
 
         Returns all details about a single redirect flow
 
+        Deprecated:
+            Redirect Flows are legacy APIs and cannot be used by new integrators. The Billing Request flow (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for your payment flows.
+
         Args:
               identity (string): Unique identifier, beginning with "RE".
               params (dict, optional): Query string parameters.
@@ -60,6 +70,8 @@ def get(self,identity,params=None, headers=None):
         Returns:
               RedirectFlow
         """
+        warnings.warn("Redirect Flows are legacy APIs and cannot be used by new integrators. The Billing Request flow (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for your payment flows.",
+                      DeprecationWarning, stacklevel=2)
         path = self._sub_url_params('/redirect_flows/:identity', {
           
             'identity': identity,
@@ -90,6 +102,9 @@ def complete(self,identity,params=None, headers=None):
         `session_token` differs to the one supplied when the redirect flow was
         created.
 
+        Deprecated:
+            Redirect Flows are legacy APIs and cannot be used by new integrators. The Billing Request flow (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for your payment flows.
+
         Args:
               identity (string): Unique identifier, beginning with "RE".
               params (dict, optional): Request body.
@@ -97,6 +112,8 @@ def complete(self,identity,params=None, headers=None):
         Returns:
               RedirectFlow
         """
+        warnings.warn("Redirect Flows are legacy APIs and cannot be used by new integrators. The Billing Request flow (https://developer.gocardless.com/api-reference/#billing-requests) API should be used for your payment flows.",
+                      DeprecationWarning, stacklevel=2)
         path = self._sub_url_params('/redirect_flows/:identity/actions/complete', {
           
             'identity': identity,