Replies to 'Bullies'

My 15 year old daughter will be going into the 10th grade this year.  All summer long she has been tormented by several girls who have vowed to "ruin" her next year.  She has always been a happy go lucky little girl and when she was in the 8th grade she won her Jr. High beauty pagent.  Ever since then girls have been calling her names and just making her life miserable.  She was able to cope but things have completely spirled out of control this summer and she has had 3 friends turn on her because of one girl.  These girls have called her, text messaged her and done everything possible to make her life miserable.  They have threatend to beat her up and mess up her face, and my daughter is now to the point where she doesnt even want to go to school.  I have called the other parents and asked them nicely to speak with their daughters about this but they blow it off and say that it will all blow over and they will all be friends before long.  I am not the type of person to blow up an issue and I know that my daughter hasnt been provoking these kids because she doesnt have access to the internet and her cell phone has been taken away and even with me having her phone they still call and text her.  What do I do?  and am I taking these things the wrong way? any advice would be greatly appreaciated.