Hi my CLK320 was only fitted with a cassette radio\n & a 6 disc changer that packed uo long ago & couldnt find a replacement . So ive bought a Becker model BE6021 radio /cd that came out of a german car . Ive fitted it into my console with bit of surgery & fired up ok but after 1minutes gives the message PROD in the display , trying to put in the codeI I was given doesnt work still says PROD . Im told that some programe is needed as it was coded only for the car it came out of . So what to do now ?