Pathetic service

Pathetic service, took my car in for a 45000 km service, I informed them of front brake pads noise, on collection they said they checked brakes and they are fine however the noise continued and got worse later in the month. I took the car back for them to check, later when I went to collect my car, they informed me that I need to pay R3 600, they replaced the brake discs and pads. I was not informed of the fact that brake pads were finished and that brake discs need to be replaced before the job is carried out. I did not authorise for them to do the job without informing of what needs to happen and the cost implications as the car just recently got off the Maintanance plan. I escalated the matter to vw South Africa, however they did not assist as it is the dealership problem.