If GMs/reps continue to ignore you I would suggest you blacklist the person. If even that fails, you may want to seriously consider taking some time away from the game. I know you don't want to let him "win", but sometimes your emotional well-being has to come before winning or losing. If this is something that is causing you stress in your real life, then it would be healthier for you personally to just walk away. (In my humble opinion.)