Sorry to hear that. Its so annoying people jealous or drunk doing this sort of thing. The worst thing is if you report it the police wont even be interested. Stronger punishments needed.
Sorry to hear of this we had our old 330d keyed down both sides from front to back it's really upsetting, we had to go through insurance & it went into BMW bodyshop they did a great job to be fair, then we sold it 4 wks later.