One of the rear parking sensors dropped out of it’s hole and into the rear fender. Thus, every time the car was being parked one sensor indicated -close vicinity, beeping on the display panel. I tried to put this back in several times but then relented, and asked the Audi garage to put it back in. After picking up the car, there was no constant beeping so I thought all was great no more constant parking sensor beeping when parking. Shortly after though, I realised the parking sensors were not working at all. I went back to the same garage and informed them the parking sensors are no longer working. They performed a computer check, and came back and said the parking sensors don’t work because there’s a fault between the towbar & parking sensors. I haven’t used the towbar, yet! They have now informed me they need to replace the sensor system which steers this, roughly $300, part only. How can this be! Any suggestions folks?