Hi in case you are with Optus on the broadband/home phone bundle (which is pretty much unlimited data and calls)…AND uncontracted to them
This will work if your current deal with them is no longer under 12 or 24 month contract - so check that first, but the current offering is $115 per month (you may be paying more it used to be $130) ring them and say "Hey TPG and aaNet do it for $79.95 so what gives?" - with a bit of persistence they will discount it by $20 (recontracting for 12 months)
They will pull out stops to retain customers. Their byline is "yes" after all…I did it and a mate did it just last week no probs. (I would go to TPG (and probably will after this contract) except I have to migrate email accounts).
Hoping this helps and saves some people some hard earned shekels (12 X 20 = $240 saved for the year)
I can confirm this works, I have recently called Optus retention and said Belong currently offers 80 bux per month for 250GB download with unlimited calls and no contract, can they match it. The rep did offer me discount on two of their plans, one being the 200GB and the other one was the unlimited plan, I can't recall exactly how much it was but it was similar to what OP has suggested. Although I'm still a little unconvinced, thinking of giving Belong a go.