//Goods bought after 1 October 2015
If you're outside the 30-day right to reject, you have to give the retailer one opportunity to repair or replace any goods or digital content which are of unsatisfactory quality, unfit for purpose or not as described.
You can choose whether you want the goods to be repaired or replaced.
But the retailer can refuse if they can show that your choice is disproportionately expensive compared with the alternative.
If the attempt at a repair or replacement is unsuccessful, you can then claim a refund, or a price reduction if you wish to keep the product. //
http://www.which.co.uk/consumer-rights/advice/what-do-i-do-if-i-have-a-faulty-product