Hello and welcome @james.booth71 
It’s no real substitute for actual offer emails, but there’s a Special Offers topic that you can have a squizz at. 
Sometimes unchecking the boxes and re-signing up again later can trick it back into working (seems to work better on Deal of the Day ones). Or, failing that, you can change your email, or sign up with another email, and that often works.
But, yes, it’s a ball-ache.