When it looks like it's gonna go bad, send all requests for payment via US Mail "Certified, return receipt requested" Some GC's know all the tricks, and we often don't. ("The bill never got here" is just the beginning of this)
Always finish your contractual obligations. The "I'll pull out all the breakers" mentality doesn't hold up in court.
Make a GIANT paper trail. FLOOD them with paperwork. Document it all, dates, times, etc.
(And if they say "You'll never work for me again", consider it a Godsend.)
