Okay so a little update after some investigation. It looks like the previous owner may have cocked up the iPod connector, it is the same as the one I have bought but it is integral to the MDI unit obviously - I have had it out of the car but it looks like various parts are glued together and wouldn't release, I was thinking I'd be able to replace the connecting cable myself and feed it back through the unit.
Has anyone had any experience doing this or can I get the unit refurbished somewhere or it is a case of spending 150 and getting a replacement from eBay?
Thanks again
Jordan