Well, i read all infos, and 1st at all, when you deposit that amount (big - 15btc) you simply need to read all rules, to know where will your money be and what will happend with that money. As i read there was mistake with ID, providing false information. For me betting with that amount is stupid, but i dont wanna about that. Every sportsbook have their terms and conditions and when you gambling with high amount you need to read carefully all that small letters
Joke on side, i am using sportsbet.io from their beggining, withdrawl over 20btc so far (never over 1btc), highest withdrawl was ~0.9btc, every week i withdrawl some amount, they never ask me for KYC, i allways get my money in about few minutes (just like about few hours when i withrawl my money).
So, point is, be carefull, read all terms, and dont put fake informations when you are betting with such a lot money.
Hope so that you will get your prize (if you bet with that 15btc as you said, coz i didnt see some pic with your bet id, or betslip).
Cheers!