Reporting hackers/exploiters
Devs posted about this not long ago, and said use Inappropriate Chat, I believe. You can read about it in the Dev Tracker, if you so desire.
Good luck.
Indeed. If you witness any of these acts while playing, please report them using the in-game ticketing system so our Customer Support team can properly investigate the issue. In the case of exploits, you can also send any reports of exploit activity or knowledge to Exploits@Arena.net to ensure the development team is aware of them.