What do you think holds the central locking code in the key?

I've come across plenty of knackered keys, plenty of knackered lock solenoids, a handful of blown fuses (which lives on the back of the fusebox) but I've never come across a knackered central locking computer.

If you are only down to 1 key already then you're fucked. You need 2 working keys for the car to program a third to work with the PATS and the central locking.