for the water leaking problem, go to any workshop and then can fix for u. apply some silicon, change rubber.. it won't cost u much. unless there is a hole in the car.

problem with the brake and gear, let other mechanics check it. ask them how much it cost to fix them. if it's ridiculously expensive, then take back to SC.

and as suggest, another SC would be better since the 1 u been visiting can't fix any of your problem.