Under the Consumer Rights Act 2015, goods should be of satisfactory quality, fit for purpose and as described, while services should be provided with reasonable care and skill. If goods are faulty, you may have rights to a repair, replacement, price reduction or refund, depending on the circumstances and when you complain; the retailer is usually responsible. Online purchases normally include a 14-day cancellation period, although some exceptions apply. Keep your receipt and contact the seller first, then check Citizens Advice or the relevant GOV.UK guidance if you need help understanding your position.