Hello Tinks mom,
I am not sure if the actual laser treatment is what is making her angery. I know I was never happy with my parents when they made me go. When I got older I could not be mad because I took myself to treatment appointments. I realized when I was a teenager why they were doing it where when I started when I was five years old they did not tell me very much about why I had to go get laser treatment. I think I would have helped.
I would suggest contacting Elissa Uretsky- Rifkin (who posted in above messages. She is a Developmental Specialist, plus she has a daughter that either had or has a hemangioma. I am not sure if she has had it removed.
You can either message her from the link above or on the front page of this website she has a link to ask her questions.
I hope this helps find you some answers.