This is where you present all the rules you expect for him to follow as a normal customer and get agreement and confirmation (add in your own, steeper policies for this one instance), go back to the beginning (if you are inclinied), fully state and re-state every possible bump along the way to the completion of this job (continuing to get his agreement) and fully disclose and remind him of the benefits for having you as his service tech (get more confirmation), then Fire his ass, once and for all.