If your current company have been servicing the system for a year without the engineer code I'd be asking a few questions.
There could also be the question that ADT own the intellectual rights to the programming of the system they did.
Or stay employed, put the hours in for a well paying company if it's the money that motivates you (we're all different) and enjoy your life in a more stress free way.
Like any electrical component the mechanical parts (relay) has a finite life, imagine how many times this will have operated, so ime for the sake of a few £'s id be looking to replace.