[spike7451]

This is a ongoing problem! What we can do is band it shut with a steel band.Problem with that is you have to cut the band to open it & reband it after.Most install crews dont carry a banding machine.
The problem with the locks is that 90% (in my estimation) of the cabs have had the locks smashed by vandels or illigal re-connectors.If the doors are vandelised,then the locks jam & the keys break.A gas key is the most common key used!
As i said before.the only option is to fit 4 x tee bar keys, ( which are not available to the public & ARE tamperproof!) 2 on each door.
Unless you hav 4 x tee bar keys you cant open them except with a big crowbar!Mention this to them & see what they say.
And there is normally a lable inside the cab (top left usually) with the cab id on it)
M