Hi, sorry for the late reply. I've thought about it, and given that no one is posting in the forums, it's pointless to offer the possibility to change user name -- which was already extraordinary, since the website doesn't support it directly. So I'll just close this thread.
If it were super easy I might take the time to do it, but it was a manual procedure and to be honest I don't remember it, though I know I'd have to deal with the separate buggy accounts on forum and website.