OMG, that is awful to see
If you park your car on the drive, maybe buy one of these £30 camera's for the outside of your house looking on your car, it may just make them think twice!!!
I think T-cut is good for getting this stuff off... A little heat also might help.
Did they cause any damage getting it off!?
Shame you didn't catch them, a good kicking would have done them some good!