Cd player in factory head unit is bad ERR message

[cuspid]

I have gmpp. My original head unit keeps ejecting my cds with the err message. Why do they want to replace my head unit with a used reconditioned radio? I sat at the dealer today for 7 hours for which I was told would take 1 1/2 hours. First they ordered the radio with the cassette not the cd from technicar and then sent out for the correct radio with the cd player and installed it. It kept ejecting my cds also with err message. I brought the car back and they finally put in a new radio. Gm is cheap