Your account is not blocked but temporarily disabled since it's under KYC verification. Although another casino allows you to still use your account when in KYC verification state but still you can do anything inside aside from browsing. This is a standard procedure of the casino for all the players that undergoing KYC verification and not only your case.
400$ profit is already huge also it's not about the amount but on what you do to get it. Blackjack.fun recently attacked by cheaters that play specific games and manage to win consecutive profits. They are just making sure that their games are not abused just like before. Stirring the issue will not gonna give you more profit are change the outcome of your case. Just trust the team since they are here for a long time with good reputation.