Was looking for some NBN deals and came across this.
Great deals, keep in mind 30 days cancellation notice.
FYI according to this comment, they perform a credit check.
Edit: Did some digging, indeed they do.
The First 6-month Discount Promotional Pricing Offer is only available to new Exetel residential nbn™ customers for a limited time. The discounted amount will appear as a credit on your Exetel invoice. You must stay on your purchased plan for the first 6 months to maintain your discount price. Should you change plans within the first 6 months your discount credit will be lost.
It's probably for new customers only ..