rear passenger door(vectra)?

i was having problems with the central locking on this door,i've tried new batteries etc,but this door has a will of its own sometimes it works sometimes it don,t.now we can't even open the door manualy.i'm getting pretty desperate now as this is the door for the baby seat & what happens if there is an accident.please don't recommend a dealer as things are hard enough.vectra 96 gls