No central locking.

Hi all, just picked up a mk2 5door, drivers door has been replaced. The remote locking works for alarm and boot but not the doors. Not even a noise when button is pressed. Locking a door manually from inside, even off drivers door does nothing. So am. I likely to find there's something missing from the door or is it something to do with any other unit? They didn't switch the lo l for the door either. Original key doesn't fit it 🤦‍♂️
One of the rear doors won't open at all from inside or out. Guessing that's a jammed lock tho and needs the door card destroying to free it up?
Many thanks for ur help in advance.
Dave