have an acquaintance who is a Lawyer and I next time I see him I intend asking him about the legality of this event.
It is compulsory, every pilot I know either has a lawyer in the family or a friend who is one. The quality of their advice would depend on their knowledge of contract law and aviation law. No disrespect but otherwise it is not worth much.
Try leaving a multi story car park without paying, the boom gate stays down. Wheel clamping comes to mind? Refusing to pay at a bar, security guard "restrains" you until police arrive, same at a supermarket etc etc
Still a really bad look.