This probably isn’t going to be much help, but that doesn’t look like the original unit (at least, it’s not either of the types fitted to UK-spec cars). Maybe the “Limited Edition” models had a unique head unit? Or maybe a previous owner replaced it? If the latter, it’s possible the replacement unit doesn’t integrate properly with the car, which might explain why you can’t get at the clock … does it display other car-related functions, such as mpg and parking sensors? Whatever the reason for it being different, you probably need to find a manufacturer's name and model reference and search for that.