It sounds like UMG have a problem, if you cant redeem the discount code, so you would need to contact them via the contact us link on the shop.lewiscapaldi.com site
-- iPhone 16 Pro Max - o2 and Spusu Xperia 1V - Spusu
-- This is not customer services and we dont have access to your account I do not work for o2 or any VMo2 /Telefonica/Liberty Global Company