Fiesta Audio 6000Cd Repair

I am a frustrated and slightly angry Fiesta owner. I have just returned from my local Ford dealership where I have had to pay for a full diagnostic check for them to tell me that my audio system is broken, precisely the fault that I booked the car in for in the first place.

The audio system is a 6000CD, the fault is that when the engine is started the audio will not light up the LED screen with any info, and will not therefore tune any radio station or play a CD. It does however seem to continuously drain the battery. This results in making the car immobile until it is recharged, when done the audio system still will not light up the LED screen making it immpossible the enter the code but does continue to drain the battery. The ford dealer tells me that the audio system is not repairable and a replacement must be purchased, and, to get me motoring again, has disconnected the audio system. I am now driving my 4 year old Ford Fiesta car with no radio.

Can anyone help? are these audio systems irrepairable? is there any good advice to resolve this other than buying a new audio system?