Gee, I feel for you. It's stuff like this which makes me hotter than a $2 pistol. I cannot believe some of the responses here. Absolutely no, you don't have to accept it. What if they bury a hatchet in your forehead, you gonna' settle for that too? What a bunch of BS that this is the way it is in aviation. The guy lied to you and without an explanation why it is reasonable for you to assume he knew he was stringing you along from the get go.
The first issue is what they said and what they did (or didn't do) don't match up. Big red flag. And no explanation from them. Another big red flag. I think you nailed it; they got you by the short and curlies and they know it. So what you gonna' do about it, sonny? The fact that they did not perform as advertised demonstrates incompetence. Okay, so maybe they're off to a soft start. Give them some more time, they're mobilized and now they're rolling along. But sufficient time for all that has already passed. It's almost like they have abandoned your job.
Insult to injury, your plane was stored for a prolonged time out in the wx without notification to you. Big liability there. In CA, most often the shop is not responsible for damage arising from outside storage. But if they were in any way negligent... Didn't think about that, huh? Didn't have to because the shop said they'd get right on it and you believed them. Geez, it only gets more convoluted the more time goes by. Seemingly, they have a calloused disregard for you and your property.
When your assets are tied up and put out of your control because you dared to take someone at their word (or work order, if there was one) there are damages incured. You have provided all you said you would provide yet they operate without good faith and the fair dealing you reasonably expect. They are defrauding you of your rightly owned property.
If it was me I'd be one the phone--polite, but insistent--going up the chain of command. Once it's determined who that one person is and (if) it turns out he is part of the problem you go beyond him. I'd give him one more chance (and let him know it's one more chance) by letting him know in no uncertain terms I want him to supply specific answers to specific questions. He has seven calender days to comply. And the conversation isn't finished until we both agree to a specific date when I'll be making the follow up call.
If anything is marginal, meaning not in complete compliance with your demands, or he does not provide a satisfactory explanation, you bring out the big guns.
You send that letter your lawyer already drafted. You notify every agency you can think of. You make your comments on AirNav. You stop payment on any funds you've sent him. You seek liquidated damages. You seek redress in any and every form you can imagine. By the time you're done with him he'll gladly pay to have your plane trucked away just to cut his lossess.
You or anyone else can say I'm full of **** but they are stringing you along and you are letting them. I've been there, boy, have I been there. Venting on a webboard is good, but you've got to get on top of this before any more time goes by. In fact, time is your enemy right now; you need to make it a priority to seek complete redress from this current status. Do not settle for less than what was originally promised.
I'd really like to hear their explanation for the delay and also why their words don't match their actions. If you haven't yet kept a communications log I suggest you start keeping one; start by recording from the best of your memory what has already transpired and from now on as it happens.
I now conclude that I've been getting the runaround since at least last week. I can't believe this! 
I don't know if I'm ever going to get my airplane... 
As far as I can figure I have no recourse either - they don't give a crap and will do it when they feel like it (and probably over charge me). 
They know I'll never be back there, so what do they care about how happy I am with them? ARGH! 
