Radio/display keeps rebooting

My radio/monitor reboots all the time. I've had the radio replaced four times now, one time they replaced it, the new radio had a CD stuck in it. Can't understand how that was allowed to happen...poor QC apparently. The last time they had my car for a week trying to fix it. Now it's doing it more than before and the dealership keeps saying they'll call me back to bring it in after they get an expert from Toyota to come fix it. It's been two weeks and I haven't heard from them. Anyone else experience this? Should I contact corporate and go higher up the ladder? If so, who should I contact? This has been going on for about 4-5 months now. Just passed 36k miles so warranty is up, but I have the receipts from the previous 4 "repairs".
Thanks