We had two users with this problem last week.  I sent Amazon two emails: one with the transactions you initiated that failed and the other with the transactions the other user initiated that failed. They sent me a response about his transactions but not about yours.  I'll write them again to see if I can get a status update, but what they said about the other user was: 

We have manually verified these transaction but customer's bank declined processing it. We have requested buyer to contact bank for the declining these transactions and asked customer to re initiate it. 

Please write back to us on  payments-verification@amazon.com if you have any questions or concerns.