I have been having the same problem sense 8/11/2017 , It started when my Auto renew stopped for some reason and i went to Re sub and could not . Every time i tried to i would get this error "The transaction was not authorized. Please contact your payment provider for additional assistance."
After days of trying and working with ESO support i gave up and purchased a 60 day card from GameStop.
But for the past few days i have been trying to buy 5500 Crown points and i am still having the same problem and i can figure out how to fix it i have all ready ...
Talked to my Bank.
Tried 2 different computers.
Tried a I pad.
Lowered browser's security settings.
Tried Google chrome , Fire fox and internet explorer.
Reinstalled java and browser.
Disabled pop up blockers ad blocks firewalls , virus programs, ext.
I made sure all my address and other info was 100% correct.
i tried 2 different Credit cards.
I tried other things i cant think of at this moment.
This problem is driving me up a wall and i want to know whats wrong so i can buy 5500 x2 before the sale ends.
Please help