Hi

Just thought I'd let you know what I did. It is actually a 2006 Mark 2 and I basically got my arm up there from the bottom and with pliers ripped the cable out with sheer brute force. I then from the front through the grill with a long sharp screwdriver and hammer chipped away at the white plastic socket. I then once having smashed away most of the plastic managed to get the driver into the groove and turned it and opened it.
After cleaning this up I have attached my own system which is basically a metal rod attached to original key barrel it works perfect every time.

I found simply pushing a screw driver into the white plastic and turning the key did not work no matter how hard I pushed or where abouts I pushed. Its a bad design simple as. It took me ages to resolve my issue and Ive got a system now which works fine.