It is possible it was an oversight on their part to just close one account and that would have been the one associated with the email address you used to request the account closure. Did you advise Rollbit in that request you wanted both accounts closed? I do sympathise with your situation but can you see the matter from their perspective? If they refund/reimburse you they are effectively telling their customers that doing the same thing will get them refunds too.

I wonder if they will post in this thread offering a solution or their side of the story at least.