flyingcheesehead
Touchdown! Greaser!
You need to get your airplane out of that shop yesterday. You're absolutely, 100% asking for nothing but trouble and a HUGE bill at the end if you don't. Get the plane out first, fight over the bill second.
This. And take a lot of notes about what was discussed, when, and what you actually agreed to. I would take a letter with you stating that you do not consent to any additional work, with a statement at the bottom for the IA to sign saying "I have read and understand that the owner of N_____ does not consent to, and will not pay for, any further work." Sadly, I think it's highly likely there will be lawyers involved at some point, so best to have your ducks in a row.
In fact, I would go to the shop with a camera and document the current state the plane is in, and then hand over the letter and get the signature. If you asked for an annual inspection and all that has been done is to look under the panel (ie, no inspection ports opened, etc), then he hasn't done any approved work and I wouldn't pay a cent.
I would verbally explain that you're sorry to have to do this, but he has lost your trust through his actions.
I agree with the others that say get your plane away from this guy and take it elsewhere. Although I fear this won’t be the end of it for you. If the guy will call the manufacturer claiming you’ve got stolen equipment, I wouldn’t put it past him to call the FSDO on you the first time he sees you flying it after someone else signs off the annual.
It might actually be worth it for the OP to contact the FSDO himself and state what happened, especially with this "stolen equipment" thing. Provide copies of the relevant documentation (and get a statement from the person at Avidyne who let you know about it). State that you're aware that this isn't something the FSDO will negotiate, but that you want to be on the record right away that your plane has been properly maintained and that because of the IA's actions you want to cover your bases. Maybe even name the new shop you'll take it to for the annual instead of this guy.
After all, if someone's plane actually isn't airworthy, the LAST thing they're gonna do is contact the FSDO! If you contact them first, then the IA reporting you afterwards is going to raise their suspicions about him, not you.