Adam Internet are pretty good, we got their 'Naked DSL' (broadband without phone line rental) for $50/mth capped at 20gb. 12 mth contract.
I hate mobile carriers here too - crap signal - no free minutes (just $350 worth of calls) ?!?!?! yep they're about 10yrs behind the UK at least.
Can't believe you got a $500 bill - that's huge.