Recently, Amazon closed my account and sent me the following email message:
We have removed access to this Amazon.com account and canceled all open orders.
We took these actions because our records show that this account is related to another account that was closed by Amazon. You will not be able to access your account, or place any orders. We also advise you not to open more Amazon accounts, because they will be closed automatically.
Due to the proprietary nature of our business, we are unable to discuss other accounts with you.
I don't even know which 'another account' they mean. But, as a consequence, I am unable to contact two sellers who sent me wrong items. I suppose, if I had any gift card balance, I'd most likely lose it. So, I consider it too risky to use Amazon gift cards. I'd better find a shop where I can buy things from Amazon and pay with bitcoins.