Looks like quite a few people have this problem with their cards. As for switching banks I'll actually be doing that in 6 months when I get married. I'll still keep the checking account open for emergencies but everything else is getting transferred.

So does anyone know how those other the premium modules to work? It looks like unless you never bought them prior to the old Bioware site, there is no way to gain access to them? Or am I missing something there?

Congrats on getting married (or perhaps my condolences :P)!

I think it may be better to ask about the premium modules in the Neverwinter Nights Game Forum: http://www.gog.com/en/forum/neverwinter_nights_diamond/#1317261403

However, from the help page I linked to earlier it states something about a module downloader in the game extras which you can find just underneath where you downloaded the full game:

Didn't have a problem with my Mastercard until my bank decided to use Mastercard Secure for transactions. Since GOG doesn't support that I had to switch to my Visa or just pay with Paypal. Not a big issue but slightly annoying.

What? That should be no deal at all. My bank also uses Mastercard Secure, but if the site does not support it, you can just pay the old way.

Well it's one thing to support it, another to be made mandatory and my bank made it mandatory. Without the secure code can't make any transaction and since there's nowhere to input said code on GOG I have to use other means of pay. I suppose I could ask the bank to drop it for GOG and maybe they'll listen, but it's a big maybe. Sometimes some banks go to too much lengths in protecting their customers. I mean, I actually had to make a formal written request to have my cards work with Paypal. And I didn't think about adding Amazon to that list at the time and if I want to pay on Amazon now I need to make another request (or just use my wife's card from another bank... simpler).
I've been a customer of said bank for quite some time and they never treated me badly, the fees are low or even zero in some cases, so I can't hold it too much against them that they secure stuff to a point where it makes it hard to pay on the internet.