YES you can possibly sue. To do so, you would have to locate the responsible party. I think it would happen in small claims court type scenario, or depending on $$$$ amount, civil court.1) Can you sue someone in this profession without a paper trail?
BUT, I should ask, how did your parents find out about this particular "contractor"?
Just some guy in a truck knock on their door, mailbox/door knob fliers, friend referred, does mom and dad know if they had a company signage on their vehicle, type of vehicle etc?
I'm asking in order to try to ascertain ways to track them down if that is even possible.