How or can I get my 600E radio/cd working again? ?

Replaced starter motor at garage, when I got it back key code was needed, tried the key code in the book and this did not work, tried another 6 times and by now I was on 30 minute waites before I could try again! Took it to Ford, serial number on audio book was not the same as that of the radio, got a key code for the serial number on the radio and tried this! Still no luck, took it to Technomend and was assured code given would work, did not try it while there as I had to wait 26 minutes so on the way home tried supplied key code! Still not working! I have spent £30-00 trying to get this sorted now and am at the point where it would have been cheaper just to buy a new radio!
Can anyone help!!