How to get redmi vouchers £15off

You need to refer a different email address to the one you register with to send the referral (obviously), but you also need to either open the referral and register using a different browser, or as a different "person" in chrome, or otherwise clear all cookies and data after sending the referral that could allow mi to link the accounts. Not sure if they check IP address too. (edited)

Google 'mi store £15 refer a friend' and click on the first link. Then click on the referral link and sign up as a new user. Once you signed up you should get a £15 coupon in your coupon section, if not wait a day or so until it appears, if not you'll be scratching your head wondering if you done it properly or not.