It's so upsetting when that happens. Back last year my car was vandalised big time - brick through the rear screen, all door panels bashed in and key marks like you wouldn't believe. We also knew, but couldn't prove, who had done it. My husband was ready to 'go and have a few words' (ahem).
It is gutting but if it's any small consolation it's largely down to jealousy and the mis-led belief that if you have a car like that, you can afford to repair the damage.
What goes around definitely comes around and next time they'll have their come-uppance.
In the meantime, Supercharged Morph recommended metallic T-Cut and it does make more of a difference. Failing that, try Chips Away or someone similar.
Failing that, we'll get a lynch mob sorted for you