Hi Mate,
It's difficult having to cope with dim wits like this but don't let em win. You sell the Zed and they get what they want, you generally find when lame brain toss pots can't get it for themselves thay have to resort to these tactics to take the shine off it for them that have managed to get it.
Rise above it, look at the long term picture... in a few months you will be out of easy reach and they will find some bugger else to annoy, look for ways of pissing them off without them knowing and don't make anything of the car being keyed just let it drop
.....as soon as know they have pi**ed you off they've won.
Wait your chance to get even, revenge is a dish best served cold.