Her parents are being overbearing and they won't let me contact her?

My friend was making bad grades (OK, I know that's not good), and her guardians pulled her out of the high school. I understand them being strict about making 2 F's on a progress report. . . But they pulled her out to go to some all girls christian private school and when I called her to ask if she was okay, her guardian picked up and asked who i was, then told me verbatim "Catherine can't going to talk to her old friends from [school name] any more, so never call again" I was one of her best friends and i haven't talked to her in over a month now. . . there's a play going on in the school and I'm ushering, so I'm going to try to contact her and ask if she can come. Can anyone pinpoint a "anger level" from 1-10 for her guardians or tell me a way to reason with them?