I clean carpets for a living and inform them of my 24 hour notice for cancellations/reschedule policy when the appointment is made. Some of them call up at the last second claiming emergencies of one sort or another. Some don't show up for appointments at all. So, generally I send them to collections and expect them to pay even if the work is not performed since I can't very well give the appointment to someone else at the last second. I don't feel like I have to underwrite their alleged emergencies. This is customary in the service industry (Dentists, Tilesetters, etc). A customer tried to cancel out 2.5 hours before a Monday morning appt (my most popular spot--actually, I'm usually booked solid and turning people away.) Anyway, in response to a collections notice, he wrote on the check he would sue me if I cashed it and refered to the Voluntary Payment Doctine. What is this all about?