If Rollbit is saying you have multiple accounts, then I believe they must have some credible evidence to back that claim up, and if they are also saying that acceptance of the fact that you have multiple account is what it will take for the issue to be resolved amicably, then I suggest you just accept, apologize and make them understand how it's a mistake, and promise never to operate their casino with multiple account again, I trust that doing this will put this issue behind and you can withdraw your money like you've always done before, there is no need arguing and prolonging matters, Rollbit is a reputable casino, and they have spent years building their reputation, they wouldnt want to jeopardize their hand work and business for such a tiny amount of money.
But if you just make people apologize and get away with doing something wrong, they will think that they didn't get any punishment and they may try to do that again. If I get off with just yelling, I will always repeat the same mistake, or I assume, I am an old man now so it has been a while since I did anything wrong like that, but there are a lot of younger people who didn't learn the consequences of their own actions so far and they decline to accept it.
So all in all, apologizing is not enough, they need to have some sort of punishment, no idea what would fit the crime the most and every casino should have their own version so I won't be really saying what would be the case here, but there must be something that deters them from doing it ever again.