Checkout impossible

Hello everyone,

I have been trying to purchase PSM-I assessment, yet cannot get past the checkout. The standard checkout form claims my credit card details are invalid (they aren't, I tried with several different cards that all work on Amazon etc.), and MasterPass is not (yet) available here in Germany.

Looks to me that the checkout simply does not work for German folks with German credit cards.

Any workaround known?

Thanks!