Through steam or ESO website? Steam I think is still buggy for some people. If you're on console I think their process/storefront can have issues sometimes too. Your best option is to contact support as they should be instantly added to your accounts.
Edited by LucidxNightmare on December 16, 2016 6:12AM
This is a common problem, it seems. Customer support will resolve it. Occasionally they reward an additional few crowns for the inconvenience. That seems to be the trend on xbox. Something also recently happened where players who had run into this problem month by month were compensated with thousands of crowns on top of the ones that they had eventually claimed through customer support.