They made me pay for nothing

I booked my car in for them to diagnose where the problem was as the car had some annoying sound which I suspected was coming from the gear box. Later on they called and said the car was fine and they do not know where the sound was coming from and they recommend that I take the car to Hi-Q. They wanted the money for diagnosing despite them recommending another service provider to diagnose the car where I will be asked to pay again. Maybe they are making business for their friends at Hi Q but that is really costly to me as customer, to pay twice for one service :-(. The lady I was dealing with is Charmane and I have escalated to the manager (Patrick Poilly) but he has done nothing and its been two weeks already.