How do I report suspected cheating/exploiting?

[Talryx]

Okay so an allied player was somehow killing unflagged horde players in WC tonight. How can I report this? I have screenshots.

*edit* to be clear I mean inside the cave but just before the instance entrance.

[Talryx]

GM's? Mods?

[Pottu]

Click the red question mark, select "Stuck", then "Still stuck, page a GM" and in the box explain your issue and put links to any screenshots or videos.