Here’s a good way you could’ve solved your issues…
Do everything on the car yourself! Since you want to stir up trouble… OK. How about you and “your new mechanic” talking shit about how Joe did this and that wrong on the MR2 and making fun of him… only to have “your new mechanic” call Joe in for help on a recent project?
Look at why you are talking shit. You paid somebody to do stuff that you didn’t plan on paying for. You are upset because your car wasn’t on the road when you got home from school or whatever… it really doesn’t seem like a big deal to me at all. If he doesn’t want to work on your car, my car, whoever’s car… then so be it. The only thing being spent is his time.