It may not be the end of the world. If it has simply been disabled than it may well be possible to reenable it then dig into it to find the fault(s) and fix it/them.
Many of us have had to do it, and it really isn't the hardest job on a D2.
Just checked, nothing obvious that has been either tampered or disconnected other than the converting from air suspension to spring.
Abs modulator etc is all still there and no mods to the shuttle valve have been done so the car is pretty much as standard as you're gonna get excluding the air suspension now being spring.
Gonna bite the bullet and buy a nanocom when I get paid so as to check and learn if it's possible to disable output signals using nanocom.
That's the only thing I can think of.