I used to contract to cunningham lindsey (and later directly) who were loss adjusters for Yorkshire Electricity, I repaired and replaced dozens upon dozens of alarms and there was never any question about maintenance.
Call your supplier and ask to put a claim in.
A friend's daughter starts next month as an area manager, starting salary is 42k with a fully expensed A4. Now I'm sure they will want their pound of flesh but still a decent starting salary.
This could all be achieved by a Texecom Hybrid system with a couple of keypads for both area's, at least then you get notification in the house when the garage is being turned over.
Can you get a cable to the garage from the house?
I doubt anyone on here will have used it.
Fancy website but I doubt it will be comparable to a mainstream wireless system.
Looks Yale'esque and I doubt 2 seconds is enough to disable any part of the kit but I'd imagine it's one way wireless in any case.
Personally I'd spend your money elsewhere.
Safest way is to enter engineer mode and disconnect the cable fully from the panel end, take a clear photo of the connections first to make connecting back up easier.