Worst Repair shop EVER!! Dont know how to fix cars.

Car Service City do not know how to fix cars don't bother taking it their specially if you drive High end cars like Mercedes, BMW, Audi etc. Kempton Park branch had my Mercedes A200 for 2 months and still the car was not fixed. They claimed over 20K from my Warranty repairs for Water pump, thermostat, reservoir bottle. Then they said Gasket has blown but they don't have the tools to fix it. I had to fetch the vehicle and took it to a Mercedes Repair workshop who did the head gasket but they tell me the thermostat Car Service City put in is not working. How did they release the car to me knowing the thermostat is not working!! The Mercedes Workshop can not touch the car now as Car service city is responsible to repair as it was claimed by Warranty.

I want my full refund and Warranty that I paid to them as they did not fix ANYTHNG!!!