As @Oshondy already mentioned. Your case is about violating the casino ToS. Probably the casino has a record of your IP and matched to a previously ban account. Or the account that tip you that amount have a problem on Rollbit that’s why your new account is immediately connected on it.

Do you use VPN while playing because there’s a chance that you use an IP share by someone who was ban on the Rollbit casino before. This kind of case is very hard to defend especially if Rollbit have a proof for account connection.