Thanks to everyone here who posted that you can have three $50 transactions at one shop to get the 3000 bonus points. When I read the email from American Express I would have thought I'd have had to go to three different stores on the list.
I had three transactions on Wednesday evening at BIG W (a $50 gift card and two purchases of $58 and $74) and the bonus points have posted today.
I had three transactions on Wednesday evening at BIG W (a $50 gift card and two purchases of $58 and $74) and the bonus points have posted today.