I'd love to see him come back to complain.
"yadda, yadda, yadda"
"Sir, did you ask, in fact, insist, on being charged in a special way"
"yes...but.."
"And did you get exactly what you asked for?"
"yes...but..."
"Wonderful, you got exactly the special treatment you asked for, exactly as you asked, glad you had such wonderful service, after all, The customer is Always Right".