Bosch Service - why are you ripping people off

Family Inderjeeth Investment T/A Midrand Auto (Bosch Service) My car was towed to This company on recommendation of my broker. My car did not want to start when it went in, I received a quote from them for over R 29 000 to replace High pressure pump, fuel pump and battery (high pressure pump alone was over R15000) my car was with them for 7 days. I told them I don't have this kind of money and will have to tow my car somewhere else, They refused to release my car unless I pay R2100 for diagnostics and strip and quote. when I collected my car they took off the exhaust pipe and petrol tank and did not put it back. I took my car to a private mechanic and he only had to replace the petrol pump, took him 3 hours and car was fixed