Perhaps change the warning system to one of points like on forum, 10 points=temp ban, 15=perma ban and a standard warning issued would be 3 points, whereas a macro one would be 6-7.
Harsher punishments for harsher crimes. Also, let players lose 1 warning point every month of being clean.
I dont think you should be handing out bans though. We dont have the playerbase to support this course of action.
