Oh mate I feel genuinely devastated for you
Had my bonnet done last year and I was well pissed off but the whole car, I'd be reaching for the razor blades. What make it even more annoying is that is so hard to convict anyone of doing it without good CCTV or an eye witness.
Don't let the police take a laid back approach either. Make sure they do a full CCTV trawl, extensive door to door in the area it was damaged and get them to check that area for similar incidents either recent or historic just in case there is evidence of a grumpy resident in the area doing it previously.
Again mate, so gutted for ya. Would it not be worth going down the insurance route?