I had one experience like this many years ago with a dentist who bought the practice of my best customer. Everything went fine for about six months, then the checks started arriving later and later then not at all. The work kept coming in. But the money did not. I told the dr. I have to put you on c.o.d. He owes me $ 7500.00, this is back in 1985. No way says he. Then start your cases over with another lab says I. I had about 20 cases in varying stages of completion. One case was a nearly finished 12 unit bridge. The guy freaked! He practically started crying. I got my money ,every dime.