gday mate, i'm using a bigpond mobile broadband stick too. I'm unsure about yours, but this is how i got mine to work; use network manager.
if you're using gnome, the applet seems to work better than kde's for this particular task, but the later kdes have inprooved a lot. I say this as a kde user, specifically talking about there network manager applet handling mobile broadband.
I stick mine into the usb, wait about fifteen seconds for network manager to detect it, then select the create new mobile broadband connection or what ever it is. Follow the prompts. It'll ask you for your provider; select 'my provider is not listed', and then type Bigpond. It'll ask you for your APN. I had to ring up Bigpond to get this, mine was Telstra.Bigpond, but we don't have the same card so yours will probably not be the same. Ring up Bigpond to get yours, they're very easy to talk to/understand people, and they'll give you your APN once asked. They do not officially support Gnu/Linux though, so if you tell them that, that's what you're using, they may get a little weird, don't know. Hope this has helped, good luck.
Don't even bother asking the guys at the Telstra shop. I did, and they were useless hollow heads with arrogant attitudes towards myself and others using Linux.