They do not have any proof of IP, country of connection, mobile device, nothing of that
You haven't mentioned anything properly in your post for getting blocked. But based on this statement, I guess FortuneJack has blocked your account and confiscated the winnings for having connections with other account. Simply, you have been accused of using multiple accounts, isn't it?
because actually their KYC as i read in few sites isnt just send ID photo, they ask actually ask you to use the webcam and make from there the KYC by scanning your ID and your face.
I have completed the KYC verification at FortuneJack. So, I can confirm that they ask the user to sit with their ID card in front of the camera to do the live verification.