the OP has a valid beef.
Forgetting the quality of the work, the least Dave could have done is respond to his emails and calls. If Dave doesn't agree with the OP, then say so, but to leave a customer hanging for weeks during the riding season isn't right.
I had a similar experience with a U.S. aftermarket seat manufacturer and it was incredibly frustrating. Take a guess who
There's another side to this story of course, but based on the OP's info, I'd have to side with him.
I did have a bike serviced at Dave's years ago and I was quite happy; but this type of posting would make me think twice now.