Consumer NZ is pleased that the Commerce Commission's investigating the two supermarket chains on the back of its complaint.
The commission's investigating whether certain pricing and promotional practices comply with the Fair Trading Act.
Consumer NZ received more than 600 complaints from consumers.
Chief Executive Jon Duffy told Tim Dower that this includes the price on the shelf being different to what's being charged at the till.
He says more complex issues include multi-buys like two for ones, but it's more expensive to buy the two than buy them separately.
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