Maintenance for the week of April 6:
• [IN PROGRESS] ESO Store and Account System for maintenance – April 9, 9:00AM EDT (13:00 UTC) - 6:00PM EDT (22:00 UTC)
PS4 player so I don't know if this will help but this is part of an email I recieved in reponse to a similar issue:
"I have added the Explorer's Pack, the Imperial Upgrade, and 1500 Crowns. We are unable to grant ESO Plus directly, as that goes through Sony directly, but we were at least able to get you the Crowns for it. As for the other bonuses, we are still working on that, and will be in touch once we are able to resolve that."