hi iv got a problem with the remote locking .it locks and unlocks when it wantts to iv put new battery in the fob but no change ..locks and unlocks fine with the key even though there is about a 3 second delay of the rest of the doors unlocking or locking after the drivers door has been unlocked or locked .the doors even lock or unlock on there own when your driving along without even touching the key fob or internal locks .anyone got any ideas .or is it a common fault .was going to change the fob but was told its about £80 but mite not even be the problem

I'd say water in the central locking solenoid in the drivers door.

Would I be guessing right that it usually happens in cold or wet weather?

Water gets between the window and the window seals.

I had exactly the same problem on my previous car, a 1999 Mondeo Ghia X, I put it down to water getting in as Stoney said, it got worse over the months until I had to use the key to lock each individual door; Water also got into other electrical bits and all sorts of things started to go belly up, it was time to get rid of it quick, now driving a 2008 Focus Estate Titanium 1.8 petrol, love the new car.

I would put my money on it being a dodgey drivers door lock motor, as had exactly same problem. After i changed the drivers door lock motor all now works perfect