My opinion is that this does not sound like a healthy normal Dr./patient relationship. My best advice is to see if you can find, if this is possible, any other patients and see if he treats them the same way. It's really hard some times to find out one's motivation for their behavior. It does seem very suspicious that every time he calls you back after you have cancelled an appointment it's about him BILLING you for a missed appointment and not about the care/support that you need for your well being unless you just have a habit of missing or changing most of your appointments. Calling 5 days in advance is plenty of time for him to fill your appointment slot. Good Luck...