Would need to check if any of these have an age limitation.
Some may need the physical card.
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Have the kids buy some petrol for the family car. Could pay cash if needed
BP - Qantas (from ~ March 2020)
Link--->
BP fuel
"Join BP Rewards to earn up to 2 Qantas Points per litre and 1 point per $1 spent on eligible in-store products."
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Have the kids buy a pizza for the family or a friend
Shopping Qantas.- Pizza Hut (Australia)
https://shopping.qantas.com/pizza-hut
Log in and search for vendor.
Earn 3 points per $1 when you click through from Qantas Shopping each time you shop
Order a pizza for delivery or pickup.
https://shopping.qantas.com/shop?id=pizza-hut&coupon=1702249
Has the option of paying cash at pickup. Have someone pick up & pay cash.
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Shopping Qantas - booktopia
https://shopping.qantas.com/booktopia
Log in and search for vendor
Earn 2 points per $1 on eligible products once you've linked your Frequent Flyer details to your Booktopia account
(Points usually credited within 7 days after the delivery date)
plus
Earn 2 points per $1 when you click through from Qantas Shopping each time you shop
(Points usually credited to your account within 95 days)
Total 4 off QF points per $1 spend
They have ebooks from $0.99 that can be downloaded, so no physical delivery needed.
Order 2 x $0.99 ebooks for 4 QF points.
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Have the kids join Hoyts. Then go see a movie. Good activity for school holidays to keep them quite for a few hours.
Australian residents can join Hoyts Reward program (movies)
Link QF account and get 100 QF points. QF points credit in 24 hours IME. May or may not work for non Australian residents.
https://www.hoyts.com.au/rewards
https://www.hoyts.com.au/hoyts-pages/earn-qantas-frequent-flyer-points