If you are a postpaid customer you can add sims to share internet with your tablets. I recently added a data share sim for $5 and received a free voucher (I had to go in chat but was sent to me 10hours after getting in touch). When you go through checkout it will show free 3 months of Netflix. Just take a screenshot for your record.
So basically you save approx $19 and also get an extra sim to share your data. We are allowed up to 5 sims for data share, however I don't' know If vouchers are stackable. Potentially we could get 15 months for $25, but I don't know if we can buy 5 all at once or/if stackable.
Just looked at this thread and it seems that vouchers are stackable too: https://www.ozbargain.com.au/node/187534?page=1
so is it actually supposed to come with free netflix or do you have to hassle them and ask for it?