I only have a key; no remote. Twice over a few weeks the central locking stopped working i.e. when I unlocked driver's door the other doors didn't. Then it started working again. Third time it has stayed not working. I have checked the fuse (and tried replacement) but no change. Key in passenger door or boot/trunk doesn't lock/unlock other doors either. Any ideas please?

 

If it won't work from any of the locks, and the fuse is fine, I would probably point at a dodgy central locking relay, which is mounted on a relay board up above your accelerator pedal inside the car.