Under the Consumer Rights Act of 2015 you have an early right to reject goods that are unsatisfactory quality, unfit for purpose or not as described, and get a full refund. But this right is limited to 30 days from the date you took ownership of the goods (this could be the date of purchase or the date the goods were delivered to you - whichever is later). After the initial 30 days, you can't demand a full refund in the first instance, but you still have the right to a repair or replacement.