Ford Fiesta Hatchback 1.25 82 Zetec 5dr how do I lock without a key?

So here's the story, my mother went away for a week and can't get back here. Stupidly enough, she took her car key with her (like she's going to need it) some people have tried to break into the car and managed to somehow unlock the doors without breaking the car.
Unfortunately for them, that car works on a key mechanism that recognises the key by an inscripted code, so it can't be hot wired.
I think they realised that after getting into the car and out of frustration the desctructive idiots decided to smash the driver side mirror.
That isn't really a super major concern at the moment, more that I can't get in touch with my mother and the car is left unlocked. I have no key to unlock it, surely if there's a way to unlock the doors without a key there has to be a method to locking them back up, right?

Added (1). Also, just to add. Is there a way of turning the power off in the car. It's on, but the engine isn't running if you know what I mean.
The dashboard and everything us all light up! Running down the battery in the process. Also no way of fixing that without the key as far as I can tell!

Could do with knowing the age of the car but anyway, a lot of the pre 2000 fords had a strange feature where any ford key would lock the doors but only the correct key will unlock them so borrow a ford key from someone and try it I know it defiantly works on a 1999 1.25 zetec fiestas and also on 1997 transits. As for the power simple answer is to disconnect the battery negative terminal.

Remove the hearth lead from the battery