Happened on Christmas Eve. Apparently I signed up for a free trial of Prime at 4 a.m., shared my subscription benefits with a "family or friend" and watched 2 TV programmes. First I knew of it was at about 7:30 a.m., reading the 4 a.m. email welcoming me to Prime.
Obviously I've cancelled my Prime trial subscription, removed my non-existent "kids" from my account, set up 2FA, and changed my password.
Reported it to Amazon but because it's not cost me any money and there are no unfamiliar addresses or newly placed orders on my account, Amazon have deemed this to not count as suspicious activity.
So wtf? Is this a known scam that might lead to something worse?