It been many yrs since I touched one...
Think the fobs are on the system as a zone, delete it.
The radio stuff was documented its own manual,
You'd be best of with co. with expirance of the product or rip the whole thing out & replace
I recall building then up from-
ADE, Elmdene or Aritech Bell modules
Kinetic Siren
Kinetic Strobe
Sometime with
Dragon? Anti foam modules
or CQR Foam pendent
The 1st complete box I recall is CQR interga, 1st one we used was a CQR Cequra
unless its been under cover or better still inside its gonna be f'ked,
they not made 'em for 17 yrs or more, we last bought the horizontal type in 1994 ish
personally I'd ditch the old controls & put a hybrid euro in.
press II & see status of the alarm.
If they can afford extensions they can afford some proper controls