Hadn't noticed this thread before today.
I was with Adam Internet for 16 years, they were originally a South Australian ISP which later branched out to parts of NSW and QLD (I think) but mostly just South Australian. I was with them for so long because they were good and reliable. Then iinet bought Adam! They buggered the plans and raised the prices. So I switched to Telstra in December 2014.
For the first few months with Telstra I had no issues but once Netflix got going we now notice around 6-7pm our connection is crap, comes good for about an hour then at around 8-8:30pm it goes crap again. It doesn't happen all the time but we do notice its always around the same time of day.
It was really bad just after Netflix started, but over time it does seem to be getting better and doesn't happen as often but it does still occasionally happen. I cant say for sure its Netflix but just seem too much of a coincidence.