I just received this email from Coles MasterCard. The offer has to be activated to work so check your inbox.
Spend on your Coles Rewards Platinum Mastercard between 10 November 2018 and 10 December 2018 and you'll receive 5% cashback on retail purchases made by both the Primary and Additional Cardholders (up to $100)
Plus, you'll also be collecting 2 standard flybuys points for every $1 on eligible spend2 when you use your card.
I got double Flybuys points