How can I report a customer?

Hello, I know this should have been in Dutch but I do know the language.

I’ve had a issue with a customer using your services, this customer is hijacking games servers and destroying them for no reason. I’ve taken multiple measures to block connections and still he took time to ensure he made what he wanted.

I’d like to know what I can do to report this client and what measures you guys can take, I have logs from the server with his IP address.