I'm not really clear on what this "stalking" is. Are they like flooding your chat window with whispers or something? Are they interfering with your ability to queue for duties, or preventing you from interacting with NPCs? Are they somehow getting into instances with you and griefing / PKing you? Is there some way they can find your real life info through the game?
I've had people "follow" my character around in online games, shouting (typing) insanity at me, but they always got bored when I ignored them and buzzed off.