Eff that - out the restaurant. This crap goes too long, too far in the industry and crap needs to end, period.

But someone else mentioned it earlier - an invoice could be a step in that direction, but your friend will most likely not see that money and court fees may be way more than what the services rendered were. Second option is Labor board to report them, third option would be letting the local councilmember who oversees the area covering the restaurant also know.

If he thinks he has enough info to take it up in a legal action, I'd be happy to help. I'm just about to wrap up law school and can ask friends to see what pro bono resources are available to connect your friend with.