Bro stop wasting your time on this forum with a complaint as big as yours. It will get you nowhere.

Go to a mediation service and force their hand to supply sufficient evidence to a 3rd party mediator that you cheated with multiple accounts.

They have an active rep at AskGamblers. https://www.askgamblers.com/online-casinos/betchain-casino-review/

Make an account there start the complaint process and wait for the casinos response. It forces their hand to produce clear evidence that you cheated or you get will get paid. It is a very good site I have used a couple times successfully gotten paid from casinos that were otherwise trying to cheat me my money.

Good luck my friend with your case. I hope you get paid your winnings.