CD player problems

I have been having alot of problems with my cd player. Its a 2001 stratus rt. I bought it used 2 months ago and it was fine up until a couple weeks ago. It is a 4 disc changer and it has stacked all the cd's on top of each other, and it says err on the display. It wont eject any cd's or let me put any in. Its not covered under a warrenty, so I am wondering if anyone knows what it could be. And how much it would cost to fix. Any feedback will be appreciated. Thanks.

I don't know if you read my previous post, but I've got a 01 R/T that won't let me load number 1, I can play and remove 2 just fine, 3 I can load but it won't read, and 4 will read, but won't come out. I've yet to take the system out and jack with it, but if you find a fix (outside of buying a new system) I'll be happy to read it. I'll let you know what happens when I fool with my head.