Right David -
It seems then the lock mechanism's are dry both doors.
Try inject all possible places on the lock with WD-40 or other general purpose spray lubing.
Especially the cam that clamps on the pillar post.
Any external visible plastic parts in the mechanism may be worn - allowing the lock to "deadlock".
Locked out of Citroen AX -neither door will unlock
Moderator: RichardW