I will tell my child to said "stop" and tell the teacher. If the teacher did not help. I will go to school with my child and tell that girl stop brother my child.
But I think you should telll your daughter to be strong. Don't let people mean to her. To teach her to say "no", don't be too nice when she meet the bad kids.
If he always complain to the teachers, I am sure he will be bullied even more frequently in the future. They should learn the techniques to play with the others. 小朋友最憎人打小報告!