If you're not receiving emails from Add It Up! Extra in your email account be sure to check your email's spam folder, junk folder, social tab, and promotional tab. Email providers sometimes route emails from new sources to these folders.
Check with your email provider to ensure emails from rewardgateway.co.uk aren't blocked. If you are using your work email address to access Add It Up! Extra this would most likely be your IT team.
Allow enough time for your email to be delivered before requesting it again. It may sometimes take slightly longer depending on the security settings on your email provider.