If a product is not of acceptable quality, the retailer can't charge you for fixing it. They also can't just refer you to the manufacturer – they're obliged to resolve your issue.
Contrary to what you might get told, you don't have to return a product in its original packaging.
And if you've lost your receipt you can use the following as proof of purchase: a credit card statement that itemises the goods; a confirmation or receipt number from a phone or internet transaction; a warranty card showing the date, price and place of purchase; or the serial or production number if it's stored on the retailer's computer.
Read more from CHOICE about your shopping rights.