If you're of traditional university age and not mature students, you're all still kids. You might be of legal age and thus qualify as "mature" by some standards, but in 20 years you'll look back and realise that, yeah, you were all still basically kids.

This explains their juvenile behaviour and why it feels right that you need to retaliate and win.

Avoid these people as much as you can. Have nothing to do with them. The best revenge here is to do well with your studies and get better grades than they do. And if you don't, at least you can say you tried your best.

If they begin to attack you physically or steal things from you, the situation is different than back at school, because you can have them cautioned, thrown off the course or even arrested. As long as you have evidence.

So if you really must do something, start making a record of who said what to you and when. And don't be anywhere alone with them.