T&Cs appear to have changed for this offer. When I signed up you had to complete the min spend in the first 5 months. Now they're giving you 9 months to make the min spend.
"Members will earn 10,000 bonus Qantas Points per month for every month they spend $150 on fuel, up to a maximum of 50,000 bonus Qantas points for the first 9 months."
Seems like this might be due to the reduced travel happening at the moment. I wonder if these new terms apply to members who signed up in Feb, before the COVID-19 outbreak?