i have an idea, why dont you suspend the bots if people report it, like receive 5 times reports you immediately suspend their acc or temporary ban, and if it was the player he could log in and verify something like captcha images while gm checking if it was bots? this game is going f2p so, i guess mass player will contribute alot on killing bots.
i have reported quite a few number of bots, but after few hours, they were still there, very annoying