ditto what chef2sail said about haven harbour. excellent mechanics there. They also stand behind their work. I had my refrigeration installed there and it kept losing coolant - after a couple of tries fixing it they took it out and put in an entirely new unit. I think they probably charged the factory for it but all I cared was that they didn't charge me a dime. I didnt have to argue or even ask. They told me that it shouldn't be like that and they were going to replace it.
They may not be the cheapest but they are good. And there are no surprises and no nickel and diming. Even if you dont keep your boat there (which I do) it is a very good place to get work done.