I think there should be and it should be the withdrawal must process.
If they will not solve this, it's unprofessionalism that can result in to ruin of their reputation.

Since the forum representative account of Duelbits wasn't active since July 1st why not just try to approach the signature campaign manager (Hhampuz) of Duelbits casino.  He might have personal contact with the owner or it might be any higher staff that will help you to fix this problem.  Because 8 days, seems enough time to fix if there's a sort of investigation regarding the big winning or if you violate the term of use, then that's a problem that will never be fixed.