Do like any other drugged up superstar would do.
Sue his ass.
Mail police in his/servers country and tell them that stolen material is used on this guys server.
I hope you have any agreement on paper
There is always a big risk when you give them files first.
There should be somewhere in there agreement for renting server that they are not allowed to use copyrighted material if they don't own it. = the server provider have to take actions against his clans gameserver.
And don't be shy, tell us this super clans name and who the guy was. This allow us to help you, by banning them from our servers.
Most gameserver admins log in here from time to time and most likely would help you in this situation.
There is always a way around everything! Not to worry.
Who knows, a friend of a friend of a friend might work on this game hosting place.
PS.
And yes!!! 12$ is low.
A good modder would take 200$ per hour
It's programming in it's finest form and only a few can do it.
If they are to lazy to learn, make them pay.
Don't sell your services out for nothing.