2003 Cadillac CTS Bose Stereo

Were you able to see why they were replaced under warranty, this could have been for something as little as the finish wearing off of the buttons. If I am not mistaken, isn't the radio and the changer one unit on this vehicle? The cd changer failure is typically a failure. You did not mention the symptoms you are having. If a cd error message, won't eject, or won't load is being encountered, it is safe to say a fault with unit. If the disc skips, and you have changed discs to determine that it occurs on more than one specific disc, than it is a unit fault. Often times people use burned copies of cd's, and these can have problems, especially on older units. You did not mention any symptoms on the radio, therefore I can offer no suggestions.

In my experience, when the factory ones go bad, better off going to a place that specializes in car audio and have them look at it.