There is the fingerprinting option not sure if that would work for you:
If you’ve already banned their I.P. and e-mail vpn wouldn’t make any difference if they use the same e-mail, but guess they are using different e-mails and I.P.s then so ban isn’t working.
Don’t know what “4h1t” means, that is a strange post there Ammonia and Bleach are definitely not safe to be mixed that generates toxic gasses.