Try PMing the admin theymos and describe the situation.
Isn't this mods' job? I don't want to bother theymos about every annoying user...
Not all the mods have the ability to ban others - only global mods (although newbies can be banned by more mods). If none have acted after you reported him, then contacting theymos might be the only way. You could try PMing BadBear, malevolent or other global mods.