hello there, its really sad but many of players use them.. its not nice when feoh/aore killing me with mysterious shadow + disparition; however how to report those players - screen or fraps with "challenger8" cheating wont help.
if you have proof of a player botting etc then you should write a ticket to support giving as many details as possible and including any screens/fraps, there is nothing the forum staff can do about ingame issues. regards.