Actually you are spot on. My in laws at their previous house had problems with kids grafiti'ing his back gate (double gates to allow access for the camper van he owned), stones, litter etc finding their way onto the camper and back garden.
He tried contacting the law who said they did not have the resource, and more or less said "tough, nothing we can do".
So he took photos next time they were vandalising his property.
Within a day the police were round, and not because he now had evidence of crimes being committed against his property. One had shouted pedo, told his parents and they had in turn reported him to the police for taking photos of kids.
The police then turned up to quiz him about taking the photos of kids! He was then taunted for a period of time by the same kids.
In the end they moved home.
So I have no time what so ever for these type of society scum and their no doubt waste of space parents. The law doesnt stand up for the right people and cant help them. Yet the scum get the support.
So, if I were in the situation you were, I would quite happily pay someone to ensure a lesson is learnt. The softly softly approach is what has got is into the situation we are now, where no discipline exists any more, and it's time it were brought back.
Thats sad...
Think rtbiscuit is right though better approach is that way then loosing your head. I used to live in pretty bad area not long ago our 'heaven' was walled off and had security gates etc to keep scum out... (that did not really work) plenty of scumbags in the complex actually and plenty of kids up to no good. I decided to instead of telling them to f-off I invited them more or less over when I was doing mechanical stuff on the bikes or cars so they could see what I was doing and have a chat about this and that, it worked real well bikes where left alone and so where the cars... and as a BONUS they all looked out for my vehicles when I wasn't there was told if someone had scouted them etc (bikes) so I could move them and change the way I looked them. I'm still today pretty amazed I didn't anything vandalised or stolen for that matter. Currently live in a very good area where some kids decided to play football outside the house and one of them managed to hit my Z with the ball and scratch the top! I had a bad day and lost it completely and told them to f off this and f off that... that sparked them coming back in numbers and move bins around and general messing... I should not have done that since I made it 10 times worse. How and ever, I put my runners on and camera and decided to go for a walk to actually catch one of them (I know stupid) ... walked out and spotted one little fecker hiding in a back garden... marched in and found this little ****'s dad sitting reading the newspaper in the garden... had words with him and he was concerned but sure his boy had not done anything wrong bla bla bla... they've not been back since but that's ONLY because the man I was talking to cared about his boy and it's a posh area, with the woman you're talking about she can't be bothered so your fighting a loosing battle there mate... either move or befriend that's my advice, the harder their background is the harder they will lash back at you and you don't want to come out to the car keyed or burnt out....