In fact, retailers can't just water down the law when they feel like it.
Businesses can’t take away a consumer's right to a refund or replacement for faulty products or services. It’s illegal for businesses to rely on store policies or terms and conditions which deny these rights. For example, policies which say ‘no refunds’ or ‘no refunds or exchanges on sale items’.
https://www.accc.gov.au/consumers/problem-with-a-product-or-service-you-bought/repair-replace-refund-cancel