SOLUTION
Site:
Hello everyone,
My card had been blocked just like you guys. I couldn't access my accounts, or log on, and my card got declined everywhere.
I called Citibank, and they said it was for those people who shopped at Target over the holidays. They are trying to prevent fraud, so they sent out new cards.
I talked to a representative and activated my new card and I was able to log back in no problem and see all of my accounts, etc.
HOPE THIS HELPS