If it's the factory 6 disc I had a similar problem years ago. Had to pull the radio out with it still hooked up and "help" the cd out with a knife. It might ruin the cd but I haven't had any problems since. If I remember right you should be able to see the cd through a smallish hole, maybe triangle shaped, and that's where I used the knife.
Not the greatest post but that's all I can remember from it. Hope it helps though!