What a rabbit hole!

Tried to send a friend a 'Gift Card', yesterday. Got a receipt for it, instantly. Minute later, another email saying they've seen dodgy activity and are investigating.
Then they say my Visa has expired.
No, it's not. It's good for another few months yet.
I, basically, lost track after that. But, I got a mail asking me to reset my stuff by following their link. (As If!!!) Return address was something like " Amazon:jd7fhb4jh6776fhj49n "
Somewhere in there, I hit them, through the main site. They locked my account for a bit. Then emailed me to say all was good and to carry on. But, by this point, having been called my real name and so forth, from So Many 'Amazon' emails? I don't know which way is up, any more.
I'm terrified of my own account.
Anyone got any ideas, please?