I did not expect such behavior from the support team. Then I found several threads with a similar problem.
if you are referring to this thread "ROLLBIT 800usd Scam,won't pay until I give them "all my other Rollbit accounts".", the OP of that thread admitted that he had previously created an account on Rollbit after digging a bit on his old emails, so Rollbit was correct with their "findings". I am not saying that you are lying, but there is a chance that they did find something that connected your account to other accounts.
No, I definitely haven't registered with rollbit before and I don't have any other accounts. I opened my only account with them in early January and have only used it from my home computer.