Like I said:
... or get a ladder.
If the worst comes to the worst, you can always ditch the power (240v and battery) in the panel and let the bell outside ring for about 20 minutes. It should then stop. This will annoy the neighbours so don't do it at eleven o'clock at night!! Do it when they're out or warn them first...
- it's only an alarm, it can only make a noise!
... or get a ladder.