If you have a complaint about the way your school has handled your report about bullying by another student you can ask the school for a copy of their “formal complaints procedure” which you can then follow.
First you would make a complaint to the Teacher or the Principal, then if unsatisfied, complain to the school’s District Director.
You may also complain to the Minister for Education.
If you attend a government school, you can also contact the State Ombudsman to look into the matter but must have tried to resolve it with the school first.