Oh, man. Sorry to hear. I would keep harassing them, the reason for not responding might be due to the fact other people have money tied up as well and are equally as mad.
What is it with cryptocurrency exchanges and shitty support? Bittrex is the same as is Bitfinex and almost every other exchange. I've had a great experience with Binance, but that's probably because I haven't needed to contact their support.
Unrelated, but nice to see another Aussie on here (I am from Queensland). I've just given you a follow on here. Good luck with getting your coins back mate and keep us updated.
Exchanges that are not well known are not as big so when there are surge of users want to buy coin it crashes. There are also exchanges that are purely phony and bitafex.com is exactly that.
There are plenty of us Aussies here in steemit if you go to this POST by @choogirl, you could ask @choogirl to be properly introduced to the Australian Steemians here.