After 3 months this should be taken up with the person or company from whom it was purchased; they have to issue a refund or repacement if the device is faulty or not fit for purpose (They then pass it back to who they bought the thing from and so on). This is the Law (Google 'Sale of Goods Act 1979' and see the government guidance). If you encounter any problems or reluctance with the seller ask amazon to act as an intermediary to secure your refund/replacement. Your contract of sale is with the vendor. Likely Amazon in this case. You could contact their customer services or alternatively Xiaomi UK directly via their website.####[['device', 'Overall#Overall', 'negative']]