It doesn't sound like it was clinical at all. It sounds like she was pissed off because you missed your appointment and questioned that. Maybe she has a problem with people who challenge her authority. Whatever. Good riddance. If it were me, and the bill was just for the $50 cancellation fee, I wouldn't pay it. Or I would mail it back together with a $50 invoice for the appointment when she stood you up along with a short message: please accept this invoice in lieu of your charge.