Thats slow, best to give bigpond a call and they should be able to sort it out for you. I use to work at a ISP and do tech support, its probably just a wrong setting somewhere.
Also could be a few of the following:
-Wireless router? is it secured? someone could be using it and capping you.
-Modem settings (ISP can check this remotely if its online)
-Maybe try bypassing router and hook in directly to your modem to test to see if the router is causing the slow speeds (first thing i'd do if i was having this issue)
-And finally try another computer to see if its PC related.
Edit: I doubt its packet loss, this is more associated with satellite internet instead but won't go into that.