I buy most of my books from Kobo (
https://www.kobo.com/ ). It works fine for me, I haven't experienced any problems, but I can't promise that they'd handle the credit card hassle you describe better than Amazon did.
I don't know how good they are with automatic transfer of books to ereaders. When I buy books, I download them to a PC, remove DRM using Calibre and Apprenctice Alf (and at the same time copy them to my private Dropbox account so I have a backup in the cloud), and transfer them to my ereader using Calibre.