Audio Systems: cd changer, mercedes ml320, bose system

Question
Have '98 Mercedes ML320 w/6-CD changer in "trunk".  Getting error message & will not play CD (original CD's, not burned MP3).  Dealer fix is replace unit ($1100).  Happened twice before under warranty and that's what they did.  Is this generally a repairable problem by good car audio shop?  If not, is replacing mediocre Bose in-dash unit with in-dash CD player (or 3-cd changer) simple change-out or a big deal?

Answer
replacing the bose system, its not easy  all amplifiers are speakers need to be replace  you can find the cd changer new here

http://www.oemautosound.com/pc-50-162-oem-mercedes-benz-cd-changer-94-98.aspx
you can also buy a rebuilt unit from the same place

good luck