double din replacement

You'll need the RCA input adapter to feed the rear/sub amp, the active aerial antenna adapter and possibly a fascia plate (not too sure if you need one with double DIN).
The power ISO will need to be modified to either just swap the perm live & ignition on (if you have one) or double up on the perm live if the stock HU is controlled by the CANBUS. This will mean you have to turn the HU on/off manually. Alternatively run a new ignition on feed from the fusebox (fuse should be Radio S-kont).
RCA input adapter:
http://www.incarexpress.co.uk/view_product.php?partno=PC9404
Antenna adapter:
http://www.caraudiodirect.co.uk/aerial-adaptor-p-211.html