Mark, sorry I haven't replied before, you may well have fixed it now, but I will try and explain what I did.
It was the passenger side front door on my 3 door 2001 hard top that wouldn't unlock.
I took out the central locking motor from inside the door, I guess you can find instructions on here for that. Then I unscrewed the cover, 3 or 4 small torque screws I think. Then unclipped the cover, I then found that for some reason the bit of plastic that the motor normally pushes sort of slipped if you pushed it in one direction. So I had to drill it and put a self tapper in to fix it. The reason I did this was to try and keep the original electrical system as normal as possible. This meant that I could push or pull the original rod and it would lock and unlock the mechanism. Then you can put the cover back on. Screw it back together, then refit the mechanism. Now you get a maplins 2 wire central locking servo. I found that if I drilled 2 holes into the edge of the door (my 3 door door trim didnt cover the bottom of the door so screw holes would show). This enabled me to attach the maplins servo to the door. Then its just a case of connecting the maplins servo rod to the original door lock mecanism rod with the supplied connectors. I think then I used a multimeter to work out which is the lock wire and which is the unlock wire in the original wiring loom. Then work out the lock and unlock wires for the Maplins servo. I then soldered the correct wires together and insulated the connections.
The description above isn't great but unfortunately I didn't take any photos and it was a few months ago. Please just ask if you need any clarification and I will try and help.