Inducing deposit by bonus activity. Freeze the account and do not allow to withdraw if the deposit does not meet the requirement

The customer service introduced that it was the platform cooperated with Capstone in HK. The activity offers bonus money. I made a reservation for 500000 and I deposited 400000 later. I do not have anymore money. I do not need the bonus money, but the customer service still do not allow to withdraw. My account was frozen with over 900000 within it. Please help.