Here is a link to PlayNC which gives instructions and a link to where you would report something like this.
http://www.plaync.com/us/support/doc_2963.html?prod=48
NCSoft are the folks that run the GW servers. You will need to sign into PlayNC. I cannot provide directions for signing on because it's in some odd location that I have trouble finding. Eventually I stumble on it after 20 minutes of looking around.
After signing on, you will be automtically refreshed to a new page. Take special note of the tabs on top: Answers, Ask a Question, My Stuff (?). For a first time user this isn't immediately obvious. Particularly since this arrangement is different from the nav system used throughout every other part of the site.
I hope this is of some help.
UPDATE: Please use Dargon's link for submitting the violation. Much easier Dargon's way since you don't have to sign-in. Mine is still good for instructions / info.