These errors clear after 24 hours, DNSstuff are aware that it is individual IP's that are responsible, and not the cache server they connect through. Like Paul M, it amazes me that whilst they know the actual IP's responsible and have a reporting route to get the problem solved, they still insist an banning the cache server(s).
Their loss to be honest, if you want some decent DNS type tools, visit
http://samspade.org/t/