I am no IT wizard but cant they sort these guys out with their IP address or something.
Also this forum should be locked to guests. You should be a member to view it.
With changing IPs and mobile internet easy to get these days, it makes things much harder.
The issue though is currently under discussion, and I've just banned account number (like) 30 of his. We have a few courses of actions we can take to ensure this does not happen again, but we have to be careful though not to impact other users in the process.
It's not enough to get someone blacklisted from ISPs, but may fall under their Terms and Conditions regarding abuse/spam/harassment.