Have a read of this:
https://www.moneysavingexpert.com/shopping/consumer-rights-refunds-exchange/#buyingfromhome
How long do I have to cancel?
- Goods: 14 calendar days from the day after you receive all goods in an order (unless it's for regular delivery such as a magazine subscription, when the first delivery counts). Once you've cancelled an order you then have a further 14 days to send the goods back.
Point is that you can return for no reason within the time limits stated so fault or otherwise is irrelevant.