Found this deal when browsing for new NBN provider.
Special Offer: Sign up to the NBN50 Unlimited plan on a 6 month contract and receive a $20 discount on the monthly
fee for the first 6 months. $79.99/month thereafter. This offer is only available to new customers and may be withdrawn
at any time.
This means you only pay $59.99 on NBN50 for the first 6 months on contract.
This has been around for a long time