Are you 'stuck' in the middle of the quest or is it a situation where they'll "meet you there" (ie wait indefinitely until you return)?
I ask because when I've had quests bug out I go do a few other quests to reset the 'mindset' of the game and so far I'm 2 for 2 (maybe 3 for 3). If you're in the middle can you go back to the most recent Save right before you started that stage of the quest?

...then do a few other quests and come back to it?
I'm also on PS3.