I tried to buy a microphone +cable on amazon on December 25th, using my EU credit card. It kept saying 'revise payment method', I tried about 6 times. I called my bank, they were very confused by it and started an investigation. In the evening, I added my EU bank account and continued to try to buy the mic/cable but kept getting the same vague message to 'revise my payment method'. At the same time, my bank account kept getting very weird messages in my list of recent transactions, that I've never seen before, every time I tried to make a purchase on amazon.de. Something about my payment method having been altered (by whom?). Amazon.de support was completely useless - didn't know what was happening. Agent 2, Milica, thought this is a part of a routine check. (Right: If routine fails all of your payment methods 12 times in a row). MShe said to try the card, even though my EU bank should have been accepted. The card, of course, still kept failing. Milica refused to pass me through to her supervisor when I asked, and said he will tell me the same thing she is.
I don't know what amazon.de is doing but they are completely incompetent (at best, possibly something fraudulent is going on). I don't want them having access to my data, so I will be deleting my account on amazon.de.
Amazon.de is the biggest joke of an online store I've ever seen. Be VERY careful when dealing with them.