Overcharged!

When my brakepad warning light went on, I took my car to Sandown where I have it serviced. They charged me R800 to check the brakes and came back with a quote of Almost R8000 for a set of brake discs and 2 sets of brake pads. When I went to collect my vehicle, they brought the inspection fee down to R427 and advised they could do the job for R5460. Why were they overcharging so much to start off with?? I took my car to Supaquick, who advised the discs need to be skimmed and sanded, and they put on new brakepads all for the price of R1700!!! They also didn't charge me a cent for the inspection prior to repair. I took the vehicle for a 3rd opinion and they also confimed what supaquick said. I am shocked and appalled that I was taken for such a ride and overcharged to this extent.