Poor service or no service at all

Last year i took my car in for service at Audi Centurion, it was a 60 000 km service. The car has a maintenance plan so they changed the front brake pads. two days later i get a warning light with a message "Warning! Brake servo inoperative", then i also got the following warning with the ABS light on "Automatic Start stop not functioning / Error Automatic Start Stop: System Fault! Function unavailable". I have taken the car back three times to Audi in Centurion for them to fix this and they just switch of the light and changed things that amount to R 12 000 .00 and a few days later the light is back. The issue is still not fixed up until now and the problem now is the light is always on. Audi is not resolving this issue and it was caused by them, the car had no problem before they replaced my disk pads.