Ford Focas central locking?

Hi i have a ford focas 2000 1.8 ghia and the central locking as stopped woking, i have reset the central locking system by turning the key etc as i have in the past and it worked but not this time. I have also changed no 63 fuse behind fuse box & unplugged the cables at the siemens central locking unit under drivers side and left for 1 hour & replaced keyfob with a new battery and still the key fob doesn't work, it works using the key but not with the fob please can anyone help its doing my head in :(