[cdnus]

My build experience started off very much the same scenario as yours. Promised a six month build "no problem". Six months later---nothing naada zilch to show for it.
I decided to make a visit to the builder acompanied by a very large gentleman & explained in the privacy of a small room that I intended to be driving my car in a reasonable amount of time.
I then visited,phoned, e-mailed him & had him send me update photos regularly.
It still took over a year, but I got my car in the end much quicker than I would have if I had left it to him.
Do not walk away from this, that is exactly the end result he wants. If you walk away he has no obligation to you & you have no recourse.
Get on him like hair on a ape, give him no rest or peace in his life. He does not deserve any, cause as much disruption as you can, he will get the message & cave.

Craig