2023 Audi A5

In mid May, 2025 I noticed at slow speed, a loud thumping noise was coming right rear of car. I brought it to the dealer on May 19, 2025. I was told to wait for analysis of the problem. After about two hours, the service advisor informed me that the mechanics had found and repaired a malfunction in the All-Wheel Drive mechanism. I was told that the car was safe to drive. Within a few days, I noted that the problem was back. I made a service appointment for June 17, 2025. The dealer kept the car for two days. At the end of that time, the service advisor informed me that the Audi All Wheel Drive system requires fluid at very high temperatures in order to function properly. According to him, I am the cause of the problem because I do not drive distances far enough to "heat up the fluid" enough to make the system function properly. He further said that the AWD system will not function properly unless I drove 20-30 miles. How does one stop if the drive system is out of control???