Vehicle returning 3 times, with same problem

In April/May my car went for service at VW McCarthy in Umhlanga near Gateway. I returned it again in August as it had squeaking noise when braking. The problem was not entirely resolved as the car was still squeaking, due to work travels I did not return it same time. I returned the vehicle last week Thursday again 16 Nov and was told it was making noise due to dirt/stones in the tyres which was causing the noise. Needless to say I paid the money for the labour and as soon as I drove out the car was squeaking again. I really do not understand what the problem is that cannot be resolved. I have paid time and again for service and advice however I still have the same problem. When I phoned the service agent, she said I need to bring the car in again for them to test drive. This has been such a waste of time and money where the problem is not sorted. I am beginning to doubt the service level offered at this branch.