Happened to me, stopped buying from Amazon just because of it.
Me too. Noticed a charge, investigated, and somehow I’d been signed up for “prime”.
I asked how it happened and they simply could not tell me (or wouldn’t). Based in their inability to tell me how it happened, I started making noise about a data breach at Amazon.
I got an immediate refund at that point.
You should check this out:
http://amazonprimelawsuit.blogspot.com/