The way the remote locking works is that every time you press the button on the remote the remote locking unit sends a pulse down the wire to either lock or unlock. What has probably happened is that the wire connecting the remote locking unit to the central locking has become disconnected ( or severed) In my car, 1998 Gal, the relevant wires are red/black and green/blue in the P5 connector in the main fuse box. Yours will almost certainly be different but basically you have to trace this wire between the central locking system and the remote module to see where the break is. if you do a search for remote locking, peopl have installed after market units to ther Gals and they will say which wires lock and which unlock