Credit card country is fixed to "United States", unable to change this

I cannot change my XBOX Gamertag with my VISA credit card. The "Add a credit card or debit card" form in https://account.xbox.com/CustomizeProfile has the country entry fixed to "United States", and I am unable to change this to anything else. My country is The Netherlands.

I only use the account for playing Minecraft on a PC. I don't own an XBOX, so I cannot change the region using the box. My Microsoft account has the correct region: The Netherlands.

Using an Xbox Gift Card is also not an option because the site does not accept gift carts from another region.

Changing my Xbox account region in https://account.xbox.com/en-us/AccountMigrationConfirm to "Nederland" results in an error message: "There’s a problem completing your move right now. Please check the Region Change Support Page to make sure it will work for you, and try again later. "

I am stuck here.

:)