I might be mistaken here. It is my impression that a chat ban only lasts 1 month. So maybe the problem will take care of itself in about 10 days from now.
If not, then you should email to Percy. As far as I know, he is the only one with the capacity to undo a chat ban.
Incidently, what I know here is mostly from experience. I was inadvertenly banned from chat late last year - apparently a mis-aimed mouse click banned me instead of the intended target.