That sucks, but if you need your neighbors to do large things for you such as maintain a field or such... I'd be inclined to just pay the kid a little bit, perhaps a bit less than you had intended, include a note about what happened and perhaps ask what happened. Maybe he had to work late and he got there as best as he could which might have been later than ideal, or maybe he had to come by before work so things were empty before you got home? Maybe he forgot how to set the alarm if there weren't written instructions and he didn't want to mess it up? Legally an adult or not, he needs to know what happened, but you don't want to get on bad terms with all your neighbors if they are close with the rest of the community. I'd just never use them again. If you want something done right, you usually have to do it yourself.