How can I Unlock MP3 CD(SONY) in Focus ?

I have got a new Focus as job car. I couldn't swich on a radio. Probably the pin code was wrong but I entered it approx.10 times and now the radio is blocked(on radio' screen indicated Locked). So the dealer said now the radio is only can be changed for another one. Is it true or there is an other way to revive the device.

Thank you in advance for the information.