Astra sxi 2006 central locking problems?

My central locking has just stopped working, I can unlock the drivers door by using the key but the other doors stay locked, even the petrol flap, the button on the centre consol doesn't work either, i can drive the car, although only until it needs petrol now.I've changed the battery in both keys, tried putting the key in the ignition, turning it once then pressing open, tried taking the battery off for about half hour, even checked fuses.... But nothing. Please help if you can