Hi, I'd like to help you with your question.
It sounds like your daughter is being bullied. These other girls have set "rules" and have made your daughter a target for not following the rules.
There are two ways to go with handling this situation. You can talk with your daughter again about reporting the bullies. See if she is willing to work with you on figuring out how to deal with the situation. Explore the options and see if it can be worked out.
You can also let her change schools. What you want to be careful of here is that she does not learn to run away from problems like bullies. She will encounter others like that in her life and sometimes leaving the situation is not an option. However, if you feel there are no more answers left and you notice your daughter having a lot of trouble emotionally, you may want to consider this option.
If your daughter is willing to work on the issue, see what has been the school's history in dealing with these types of situations. The school should at least have an anti bully program. Have you spoken to other parents about bullying in the school? You can gage what kind of reaction you might get if you decided to talk to your daughter's teachers by what other parents say. I can't imagine that your daughter is the first child affected by these bullies.
Have you spoken to the school counselor? You could call just based on wanting advice, not for her or him to interfere. See if they can give you a good idea of how the school will respond and help your daughter.
At the very least, it is important for your daughter to see a therapist. She is being targeted and needs the support of a therapist, who can not only help her find ways to cope, but help you as well. You can also bring up the idea of talking to her teachers again while she is in therapy and see what you can work out. Ask her doctor for a referral. Or if you want to search on line, here is a link to help you: http://therapists.psychologytoday.com/rms/.
Keep talking with your daughter about her situation. If you can keep her talking about it, you have a better chance of catching any changes in her behavior, indicating it's getting worse. It will also keep you up to date about the situation. Giving your daughter an outlet will help her as well. Does she belong to any sports or activities outside of school? Keeping her connected with her friends and others who appreciate her outside of school will help her deal with the situation at school and let her know that it's only part of her life, not all of it.
Here are some books that can help you:
When Your Child Is Bullied: An Essential Guide for Parents by Jenny Alexander
The Bully, the Bullied, and the Bystander: From Preschool to High School--How Parents and Teachers Can Help Break the Cycle of Violence by Barbara Coloroso
Bully Blocking: SIx Secrets to Help Children Deal With Teasing and Bullying by Evelyn M. Field
You can find these books on Amazon.com or your local library may have them for you.
I hope this has helped you,