I know who you're talking about. That child has been using that cheat since back in the old Lordaeron days. The only solution is a permanent ban, he got a ban once from what I know but it was only for 30 days.
Pretty much every old player knows that "that priest" was hacking on molten lord and is still hacking now. You are right, he did get banned in the past. It's time for a new ban and not just him, there are a lot of people in that guild who hack.