School bullying are part and parcel of growing up.
However, we need to look at how physical it is during the assault. If it is getting too violent, I would advise my child to bring a small weapon to school as a safeguard eg penknife . In Times of need use it as a defence tool rather than a counter attack. Those bullies confirm will be scared and back out.
Do not think that I'm crazy to recommend this becos you will be naive if you think you can rely on the school to settle this for you. And do not be stupid to settle this yourself. Look at the eg and the parent ended in 7wks jail. Let the child settle it by themselves with your guidance.
I myself was a school bully KNN KNN