Bad Service (Rip-off )

Bad service ever received. I took my car in for major service, I drove it there in the morning working perfectly fine. Later on they called to tell me that I need to pay 20k for my car to be fixed as they mentioned few things, I refused and told them to just do the service as planned because I didn't have any issues with my car. When I now had to drive my car out of their workshop, I started having gear issues, I told them and they insisted that my car was like that when it came in.....its now impossible to drive the car as selecting gears is totally impossible. It was my first time taking my car there and I regret it.