[OMFG!You'reActuallySmart!]

I assume you've already told the teachers and principal as well as your parents but to no avail. Even if the school does intervene, it would probably antagonize the situation even more because the penalty would be light and the bullies would be pissed off. They may also mock you by giving fake calls for the teacher.

When the sarcastic guy makes comments to you, then give the same/similar types of comments back to him. It may antagonize the situation but if you can stand up for yourself and verbally take out the bullies, you'll become a harder target.

One of the ways you can do this is to first have a decent sized audience of students watching. From there, say to them they must feel so pathetically weak they need to bully a weak, smaller and defenseless student. You can then egg them on to do something so they can show everyone how proud they are they can win a 3-1 fight against the smallest and weakest student. If they say an insult about your clothing, you can say the only reason they have their clothing is because their daddy and mommy have a big wallet (this assumes their clothing is fancy and expensive). The goal of this is to humiliate the bullies by emphasizing their actions, even though other students already know of the situation, when you do it likes this, you begin to reverse the power differentials.

You have the right to defend yourself, however, it may just lead to greater problems. The girl can cry abuse and other guys can see you've hit her or did something to hurt her, violating the traditional culture that boys cant hit girls. The better route though would be to have witnesses and ideally record the incident. If there are bruises, then document them and keep doing so over time.

Once you have this evidence, go to the principal and demand (not ask) he/she does something, then show the video evidence. Tell the principal you're going to file a police report against the girls and against the school for not providing reasonable assistance causing bodily harm. Furthermore, threaten to bring the story and evidence to the local newspaper because you've had it with the insufficient discipline from the teachers and principal. At that point, if the principal has a functioning brain, he/she will give in. However, even if he/she does give in, still issue a police report against the girls.