[Ronny]

Please read subject.  Sorry all new to me.
I have a central locking problem.
I use the fob to unlock the car and the rear door does not unlock. Occasionally it unlocks?
Please advise.  Thanks to all

[The Gonz]

Welcome, Ronny.

A search of the forum will likely reveal causes to include an ageing solenoid in the mechanism of the offending door as well as an ageing car battery.
As a '12yo', and therefore an FD model, this wouldn't be surprising. There may be some improvement if you manage to clean and lubricate the lock for that door.