Moved to Forum: Original Link
Logged into my account and redeemed the extra year. No issues.
Apparently there's an issue with claiming this through the app so it's best to try on browser.
On browser; sign in / register
a) Existing user: sign in
b) New user: register accountClick Redeem next to Help (at the top)
- Enter code
Credit: HotUKDeals
fyi you gotta use UK VPN to redeem the code