Yeah but what do you expect them to ACTUALLY DO...?
If some guy who you have identified is using impersonating you and going around doing illegal things then that's a matter for the Police.
Facebook are pretty responsive in my experience. I report pages/people every now and again and usually get a quick enough response.
They have a significant office in Sydney with some decision makers in it but in New Zealand just a sales outpost in Auckland.
If you desperately want to talk to a person I suggest Googling their Sydney office and trying them there. Odds of success: zero unless you have a clear idea of what you would actually like them to do on your behalf. Just telling them you've found a bad man is a bit of a meh moment.
One would assume either investigate if the person is exploiting a secutiry loophile, or close the account.