Agreed,
They should at least notify users with open positions or provide something that will protect user positions especially that their trading platform is focus on risky trading(leverage trading) while they do an unplanned maintenance.
I don’t follow this case but at least they should compensate the user that affected by their service disruption.
In defense, rollbit said that they pinned a notification on their website chat so users get notified. I don't think every player like to chat or pay attention to what happening in the chat. So, how your traders are going to know about your maintenance if you do not inform them via email? If OP creates a flag against them, I am going to support it even though my feedback or support does not matter much since I am not in the DT network. Rollbit should apologize for the inconvenience and they should credit the loss to the users, or they should receive negative feedback from the DT network.
I am going to step forward and tag them first.