My V70 central locking

[TomB]

Hi i have a V70 on a 52 plate,my central locking has started to play up. My key fob is not working to lock it but you can hear it trying to unlock when you press the unlock botton.Inside the car you can press the lock botton and the car will lock but unlock straight away.
The passenger door lock does not move at all either.
Anyone have any infomation or idea's what it could be.

Thanks Tom B