Jorge,
Six months of dodging you on a bass that's over a year late doesn't sound like the act of a business with a great reputation. Maybe I'm a bit cynical, but I can't think of any way to justify a refusal to respond to your queries for an extended period of time. You deserve at least an update. Don't let your obvious respect for the reputation of the builder turn you into a doormat. There's no business relationship where being ignored is healthy.
I would also seek out any connections that might help you get an answer as well. Are there any known players or associates that support the builder who you might reach as a go-between, someone the builder might listen to? You could even ask for contacts and references in public forums (like TalkBass, for example) without detailing the nature of your situation. Just post that you are trying to reach the builder and having trouble. Maybe someone out there will be able to help you get an audience.
Demanding your instrument be delivered this week would be messing with the magic. Asking for the status after several months is extremely reasonable. Also, with the claim a year ago that they were just waiting for electronic parts, it would seem that most of the magic would be long since done.
I think that, by now, I would have lost faith in the builder's intent to ever deliver a finished instrument. At a bare minimum, I would be looking into my alternatives to cut the losses. Credit card company policies, legal recourse (breech of contract? fraud?), and gathering together all the relevant documentation in preparation for action.
Despite your situation, I hope you get through to the builder and get the bass you were hoping for. Good luck!
-Bob