I had the same problem with a psychiatrist. She cancelled on me multiple times the day of but the one day I was 20 minutes late (5 minutes past the 15 minute window) she refused to see me. This was after seeing her for two years and never being late once. Not ONCE! I also lived 45 minutes away from her office so I thought she would have been understanding of the fact that I was late because of traffic that I could not control. I ended up completely freaking out in the office and I refused to go back to her. She never once called me to see if I was okay. I myself am now a psychology major and I still believe she acted in a completely inappropriate and uncaring manner. I stopped seeing her and found someone who has genuine concern for me. The change was great for me. I don't know if it is possible for you to switch therapists but it is a suggestion.