I do have a witness though. Megan was right behind me and saw it all.
I suspect you are probably right though. I didn't leave a dint on the car so if he denies it, that's about the end of the matter. I should have left a dint.
As for people throwing things at you, there is a way to report litter bugs to the EPA.
Go here... http://www.epa.vic.gov.au/Reporting/litter.asp
and register yourself. Then you will be able to report litterers. You can also print out a form and mail it in if that's easier.
I know someone who recieved a fine in the mail one day, so the sytem does work to some extent.