How can I find/get unlock codde for a Ford Cassette Player ?

It is my wife's car, a Y reg Ford Fiesta, together witha radio cassette player, however the FIESTA was purchased second hand, and we do not have the unlock code. as due to a flat battery, the display is reading CODE.I am unable to remove the player from the housing, and is there anybody out there with the know how as to how recover the code, without paying through thte nose at a local Ford dealer !!