I too, am getting a 401 error every time I've been trying to upgrade my account to the collector's edition.
I hope this problem will be fixed soon, indeed, FFXIV:ARR is an amazing game, it would be a pity to see it
being ruined by a poor customer service.

However, I do hope that this issue will be solved soon.
The problem is not coming from the customer's end but SE's, I have been trying to purchase games on different websites with the
same card, and everything worked perfectly fine.

Also, from what I have seen, it isn't a 'small' group of customers, but a massive amount of customers, who are experiencing this.
The other part probably pays with game time cards purchased in store, which would explain why there isn't more people complaining
about it.

I wish you good luck and do hope to see this glitch fixed soon.
Have a nice day, -Kami.