I use Amazon quite a lot. I ALWAYS remove my CC info as soon as I get the order confirmation. Never store CC info anywhere, it is merely asking for trouble. It is not much trouble to re-enter the CC details on the next order, but no worries about someone hacking it.
Yeah Gmail's spam filter has been not as good as of late no matter if you reported the email as spam you would get another one that is similar afterwards. So i just used the block email feature. Amazon has two factor authentication now. So if you are having issues with your account you can enable that which should help. I had issues with my Nintendo account having compromised attempts so I enabled two factor authentication on my account and the compromise attempts have gone away.