2007 sts CD Changer
 

I am having a problem with the 6 disc changer in a 2007 sts. The systemwill not play or eject a disc. I can hearan occasional clicking soundlike it is trying to switch between the cd's. The nav screenwill display "changing disc" or"ejecting disc" but nothing else happens. I know there was not an extra disc jammed in there or anything because I am the only person who is ever in the car. All other sources (XM, FM, AM) work fine but when I switch the source back to CD it will still show "changing disc". /Does anyone know what the problem is and if I take it to a dealer how long will it take to fix? Thanks in advance for any suggestions?