They can afford a corvette, a nice F150 or 250 or 350 plus 4 more vehicles and are printing money at their restaurant but need to rip you off? Their busy restaurant would have a cockroach infestation if I lived there.
Wow... I think I'd contact these folks one time and have them pay for the additional washes. If they refused or didn't see it they'd be on my Facebook getting publicly shamed for some period of time (until they paid).