It’s the $5 packet of Oreos that Woolworths says shows its discounting was real. Having been accused by the competition regulator of misleading shoppers with imaginary promotions, the supermarket giant has now put the humble chocolate cookie at the centre of its defence.

This is how supermarkets set prices, they say. The Oreo Family Pack Original 370 grams was being sold at $3.50 in late 2022, having been discounted from its normal price of $4.50. Then came requests from the manufacturer of the Oreo, Mondelez, to increase the price. Woolworths agreed, and the shelf price went up 50¢ to $5. There it stayed for 21 days. Then, Mondelez agreed to put in place a discount. Oreos fell to $4.50 in late December.