yeah i've had it happened. it was an automated account closure due to the systems they have in place. when mop first came out i got realm first leatherworking and learned all the pvp gear recipes you bought with spirits before everyone else, crafted a lot of them and put them up on auction for high prices. i guess since the items had never been listed before and there was nothing to compare it to it sets off red flags with their "smart system" I got booted from the game randomly after that and when I tried to log back in it said this account has been closed, i then received an email from blizzard that said reason was "exploiting the economy".
and when i talked to customer service through their web form system i was also told it appeared i was using a proxy service(which i don't use) told them the isp i had been logging in with all the time. i ended up having to send them a picture of my id which matched the address they had on file and a picture of a piece of mail sent to that address in my name, then they reopened my account. major pain in the ass.
the worst part is i have always had an authenticator. so having one of those attached to your account does NOT protect you from setting off false positives and getting banned by their system