I was trying to buy SpellForce earlier today, but when I checked out, it told me my debit card info was invalid so I checked my info and tried again, same thing.
I then tried my other debit and I got the same message.
So finally I went in and payed with paypal and everything was working but once I finished the payment, it charged me and sent my back to the cart with SpellForce still in there.
After I got on to my bank page, I seen that now I have 3 charges to GoG for 9.99 and a charge on paypal and still no SpellForce. :(
So... Now I am waiting for this issue to be resolved.
But I was just wondering if anyone has experienced the same problems I have :S.

I hope you contacted GOG support on this. It sounds like something went seriously wrong with your transaction from their end and they did just recently do some work on that aspect of the site.
In answer to your question, the only problem I have encountered is my Mastercard failed to work a week or two ago, which was also happening to several other people at the same time. It turned out to be something on Mastercard's end though.

I did contact support about 5 hours ago so I will see what they say about that.
Mine is a mastercard debit so that could be the reason why that went wrong, but I see no reason for the paypal to mess up.

Yeah, a similar thing just happened to me and I've contacted support, so hopefully they can help.

Other than that one instance where my transaction failed, I have never had a problem using any of my cards on GOG (debit or credit), so I don't think the fact that you were using a debit card could be the issue.

I had this problem earlier as well. I attempted to pay with my mastercard but it didn't work. Thinking there must have just been some problem with the process I tried again. Realized I had been charged both times when I checked my credit card account and still no game. Its important to not though that if you were charged to a credit card in this manner it was most likely a temporary authorization and you shouldn't actually end up getting charged twice once GOG corrects it.

Got the game. Thanks :)