I'm a teacher, and we have bullying going on in my school too. I'm a middle school teacher. We're supposed to have a "no tolerance" policy, and EVERY inquiry is supposed to be called into the cops, but they're not!
Oh, and about asst. principals and principals not being on the same page....it's like that in our school too. The right hand doesn't know what the left is doing.
If your son is seriously afraid of this girl, take it as high as you can honey, and don't back down! It doesn't matter if the principal is making $50,000 or $500,000, he/she is there to do a job, and if he/she is not doing it he/she shouldn't be there! That's just MHO.