Actually I read that you rebuilt the lower harness.
Is there any old harness or wiring in your engine bay?

If this guy changed all these items to fix the problem, and it is still not fixed, I would really stick-it-to-him. You probably won't have to go to court if you show up with your evidence and present your case to him. If he's smart, he will realize that he will lose to you in court.

These mechanics have to be held accountable....not just change a bunch of parts and cross your fingers.