Don't take this the wrong way but i really hope this wasn't Zed envy. Its not like most E85's like ours are worth massive amounts these days. I really hope this was just young idiots who would have tried this trick on any convertible saw, whether it was a battered £500, 25 year old MX5 or £200k Ferrari.
That said ,however if your phone is damaged or the car is damaged in some way, (even if it just needs a proper valet) tell the Police you want to pursue it as criminal damage, or even assault if any of the liquid went on you. If memory serves a section 59 relates only to "vehicle used in a manner causing alarm, distress or annoyance". Or ask the police for details of the culprits so you can pursue a small claim court thing.
Even if you never saw a penny from the little scrubbers a CCJ (if they didn't have one already that is) would no doubt make there life financial difficult for 6 years, as they would be unable to lend money/bank loan/credit card etc unless they get one of them "pants round your ankles and bend over while we shaft you jobs" This would have more or a lasting legacy for them than a telling off from the cops!