You shouldn't take internet seriously. If someone insults you, why would you care? A random person on a game typed in a few letters, and that should make you cry? Think about it. They can say everything they want here. If they were in real life, it would probally change, but you shouldn't take it seriously here.
While i do agree about the serious racism there, just leave. Go find a other server. If you're not content with every community on every server, leave. Play something else if that doesn't hurt you.
HOWEVER, if there are indeed 3 guys who changed their names to something insulting, then yes, they are only here to ruin the other players fun. They should be banned indeed.