Make sure you take a DATED picture of the machine you got back uncleaned but charged for. Show inside the bobbin case area where it still has fuzzies, etc and have a witness. Better yet, take the pic in front of a notary public. That could be the first step in proving this guy is crooked if you end up in small claims court. Once that is shown, nothing else he says will be credible. I would also go back to the shop with a police officer to get the other machine as just their presence sometimes will "change their attitude" and at least keep it civil. And I would tell EVERYONE I know about this shop as a warning!