I have my own security business installing alarm systems, CCTV systems etc, the best thing you can do is have it serviced once a year to make sure everything is in order and any problems will be picked up straight away. People have this general conception that once you have an alarm installed then thats it for life unfortunatly its not as the most common fault is your back up battery in the alarm panel failing after a number of years then you baisically burn the back of the alarm panel causing a number of faults including going off for no reason in the middle of the night. Hope this helps a little.
Mine gets serviced every year and the battery changed every 2 years.....but then I have a good supply of free batteries!
Only time it goes off is if I set it off by opening the garage door without dissarming it!
I have to say that I think the maintenance timers and not providing the engineer codes/boss engineer codes to the customer is a little naughty.
Mine is serviced every 12 months as well, never gone off without reason since fitted, 18 years ago.
No movement sensors, just impact and closure sensors on all doors and windows.
Was gonna suggest you've got a mouse AA and to fit pet lenses to the PIR's but as you havent got any......then maybe not

I used to fit alarms years ago, when the 1st cordless ones came out, not the crap stuff you get in diy stores mind.......and used to take along a qualified electician with me.....he'd do the wiring part, id do the wireless bits, not that i couldnt do it, just so my arse was covered if anything went wrong.
I remember one customer i had to fit pet lenses on all the PIR's so their bloody cat didnt set the alarm off......well if it decided to climb up curtains or get up anywhere high up it would set the alarm off.....but what can you do.......when there not prepared to shut it in a room without PIR, when they are out
