1. Create a new Service: "Old API" 2. Create another new Service: "New API" 3. Create an Application Plan for both APIs: "Old Plan" and "New Plan". 4. Create an Application using the Application Plan "Old Plan" (which belongs to the "Old API"). 5. Use "Application Plan List (All Services)" to fetch the ID of both Plans. 6. Use "Application List (All Services)" using the `plan_id` from the "Old Plan" to fetch the ID of the Application created in the step 4. 7. Use "Application Change Plan" and provide the `plan_id` for the "New Plan". Expected Behaviors: 1. Application will start using the "New Plan" and change the Service to the "New API". 2. 3scale API forbids switching Services - on this case, it will not change the plan and return something other than 200/OK, informing that it's only allowed to change to a Plan belonging to the same Service. Current Behavior: Application starts using the "New Plan", but is still linked to the Service "Old API", which doesn't have the "New Plan".