In my country, recently more reinforced than before, most any purchases made online must go through a second security layer, usually a code sent to your phone
The problem is, this works on a pop-up that most sites understand and redirect too. With GW2's in-game store technically being a browser window, it attempts to make this pop-up, but can't. I couldn't tell you why it can't, but it makes it impossible to buy gems. I have no nearby game stores that sell gem cards. Do we have an alternative way to purchase gems? I have no retail stores that sell cards anywhere remotely nearby.