How to PROPERLY handle dispute with mechanic?

go to another mechanic and get their opinion on it. sound like this one is going keep making up stuff to make more money and if you piss him off Mechanics have ways to make things accidentally happen like a busted oil pan or a broken radiator hose. it sounds like he is going do something to the car if you leave it with him again. get a opinion from another mechanic to be sure what it is.