Exactly Mark, what can you do?
It's exasperating to say the least but the repeater abusers seem to get a thrill when anyone complains. The same sort of idiots that smash glass bottles on cycle tracks never to see their intended victim but knowing they may pig someone off with a puncture.
We've got a VHF repeater abuser round our way - His genitals must be really extremely sore that he can't find anything better to play with.
Luckily everyone ignores him despite his 'best' efforts.