Betrayal Quest WoesFollow

Alright i killed all the orcs, and killed all but one of the rare spawning NPCs: Glen Mostyn lvl 17 heroic. i finnally after a week foubd him tonight and searched for playes to help me take him down i telled, shouted and invited but no one would help me. I was following glen sneaking and Poof! hEs gone! Wtf!? At least keep the guy long enough to form a group makes this game stupid because you have to kep logging in and out hoping theres gonna be a spawn. This is a problem with everquest i could understand if it the quest was for an item or something but this is a hallmark quest. Bah!
p.s if anyone knows spawn times that would be helpful