The 70 Duster......
Bingo...you hit the nail on the head when you disclosed you paid em' 75% of the $$$ already.....NEVER...EVER...pay anything untill the job is complete...painters are no different than most any other labor you hire....I had to learn that lesson too when building a house....the minute almost any subs got a "draw" they became MIA....I learned fast not to pay a penny until the job was done..to my satisfaction including cleanup....SHAZAAM..things started getting done.
Unfortunatly now...you are between the rock and hard place...it is very difficult to get someone to finish some other shops work.....but I would be pro-active about it and NOT allow it to sit in the corner....that is BS
Now get out there and get this thing going!!!...(hope that didn't sound too much like your wife)