My wife wants to exchange a 2 day old iPhone 14 Pro for a Samsung Galaxy S22 Ultra. On returning to Harvey Norman they refused to swap saying that the warranty on the phone had already begun and they couldn't exchange it. He also mentioned because she had registered the iPhone in her name it was not possible. However in the Apple Store they have a change of mind policy. It says you can return it within 14 days to the Apple Store https://www.apple.com/au/shop/help/returns_refund
Do Harvey Norman have a right to refuse to exchange the phone? It is in original condition. If your curious, she doesn't like the camera. It's OK for scenery, but not people.
Unless you were told by the sales guy, it doesn't need to be fit for your purpose, it just needs to be fit for the purpose as advertised. Otherwise you could keep "buying" a new fridge and return it because it didn't bake your cake.