Server Admin can't ban people

Hi, so we have some modders who have joined a server I play on. I’ve been talking to the admin for my server and he’s told me that he’s tried banning them. But they keep joining. They seem to have an infinite amount of c4 and their going around destroying everybody’s places and we can’t stop them. How can we get rid of them so they can’t join our game anymore?

Thank you

Talk to the person hosting the server , i’m sure they can help you with that (it’s what you’re paying them for)