Did you put all 250 on one bet? Did you make any other bets? How did you deposit the funds?
From what I understood is that OP made a deposit via card, placed one bet, withdrew $450 and SB seized all remaining funds.
sportsbet.io successfully approved my documents, but I started playing a few days later.
Can sportsbet confirm that they approved your documents, accepted bet and refused to partially payed you?