Info directly from the product page (with important dates highlighted):
Better than half price - get 8GB + 22GB Data Bank bonus on your first five $30+ recharges on Telstra Pre-Paid Max™.
Activate by 5 February 2019. For use in Australia within 28 days. Recharge required to access Data Bank (capped at 200GB).
Discount ends 20 December 2018 11:59pm AEST. Online only, limit 2 per customer.
Edit: this kit is also available from Coles until 11th Dec: https://www.ozbargain.com.au/node/420974
I got one of these from Coles yesterday too, wasnt advertised as such but scanned as $10 :)