I'd suggest reporting them, but that never does anything. I'd say get back at them. Use their own tactics against them. It's not the most honorable thing, but I'm not gonna act like I haven't cheated before out of revenge. Believe me, if you play with nothing but cheaters, you're gonna learn how they do their tricks.
However, if you don't want to get your sweet vengence that way, find out where those fuckers live and show them a few of your guns.