They had alot of problems with some spammers on a Metal Detecting forum board I go to alot. The guy that owns the forum got the IP address of the guy spamming, called the local authorities and internet provider.

From the little I was told about the case, the police got involved with other authorities and the internet provider immediately stopped his service. If you can just get the internet providers you can contact them and they will stop their sservice.

All interent providers have a clause that they will stop any service to people spamming, causing unwanted harrasment or unwelcomed post per the site operator.

So I would suggest you try and get the IP address, find the provider and contact them. Hope it helps.