08 Focus Central Locking Remote Problem

[focus87]

Hi all, hope someone can help,

When I use the key fob to operate the central locking on my Focus, I have to use it stood right next to the driver or passenger doors when I move away from these areas (even stood infront of the car)nothing happens. Changed the battery twice and cleaned the contacts with alcohol wipes but still does the same. Find this very frustrating as it defeats the object of having remote central locking. Car is a 2008 Ford Focus Zetec petrol.