As it is a saloon it is best to get it sorted since once the getaround fails there is no way in apart from jimmying the boot.
Same with my drivers door mechanical lock (wrecked by a local toerag), I carry a spare keyfob battery everywhere, just in case.
You might get away with drilling a hole in the rear passenger seat, behind the ski/armrest to poke around with a long stick (drill a second next to it for looking in with a torch)