Bad Service

I bought a pre-owned car at Avis Car sales in Choolorkop, Kempton Park, After few days i complained about the noise the car is making when i brake, so i thought its brakes, took it back twice and their mechanic told me there brakes and disc are still fine, they still have 50% lifespan. I suggested they must take it to VW but they were not willing to pay. I took it for service on last week Thursday and that was 6 months later after my complain. and VW advised that my discs are worn out. which is something i knew about because i have been complaining i just didn't have proof. so now am expected to pay. They delayed this whole thing so that they can tell me that i cant complain about this 6 months later.