2007 Vauxhall Zafira rear ns door lock

Recently my rear nearside lock deadlocked and would not disengage After much messing about I have managed to get it to open and replace it.It worked a few times but has deadlocked again Again I have managed to open it by lifting the door handle whilst pressing the key fob. I have now disconnected the wire to the lock which now opens and shuts but obviously cannot be locked . I have also noticed the the front n/s door also dead locks and will not disengage when this and the previous lock was connected. I have checked the wires going to both doors and there doesn't seem to be any problem Does any one have any ideas please