Very poor service

I have take my cherv utility bakkie to them for brakes to be sorted out on the 20/21st December 2018 was told brake master was damaged and need to be replaced at a cost of around R6400 i told them to go ahead with the repairs but I have been back to them about 6/7 times to date for the same brakes problem and my vehical was kept with them for abt 20 days over this period. I finally got tired of them and called customer service they have arranged for the bakkie to go for a second opinion to another branch now they come back to me and tell me the brake pads and discs are damaged and im liabil for the repairs. How did they not diagnose that on the numerous times the vehical as been to them?????