Good news, turns out I was smart and screenshotted transactions in the past - here is some evidence!

http://imgur.com/6WAwsAu

As you can see, suddenly im charged the withdraw sum again when I've mined 300 SXC. Landing me at minus ~~700sxc. When I was refunded 1K for "failed transfer" I got +300 in balance, which should have been 1.3k.