the problem with annoying chavs is that if you try to scare them off and dont do it right it makes them worse and you will wish you hadnt done anything.
You will always find there is one of them in the group that fancys himself in a rowl. his the 1 that you wanna catch late at nite with a balaclava on and make it so him mum wont reconise him.
The other route is to get a cheap camera and get evidance to prove them are causing damage.