Sorry for the delay in replying. Work dragged me away for a couple of days. Thanks for the reply.
The CD and radio both mute when a call is made or received, but when the call is over, the music starts again. The CD button on the touchscreen shows a stop sign when the phone is in use.
I thought this would be the stop or pause button as well but, obviously not!
Maybe there is a fault but, before going back to the dealer, I just wondered if any others users had the touchscreen unit and whether they could say for definite whether there is a way of stopping music without turning the unit off, turning the volume down or ejecting all CDs.