Vauxhall Astra 56 plate central locking not working?

Boot is locked, key only locks and unlocks the driver's door. The petrol cap is unlocked as well. The radio works intermittently, but when it doesn't work, it comes on when the back passenger door on the driver's side is open?
Have tried the tricks suggested here previously - putting the key in, turning to the first setting so that the radio comes on (no sound though!), pressing the unlock etc. We have also disconnected the battery in the hope it resets, but again this hasn't cleared the problem. We find it strange that there is no manual over-ride to open the boot or to lock all the doors with the key?