Unable to withdraw money after the deposit reaches the standard

I deposit 1 million for Vip and said I could withdraw it immediately, but the withdrawal did not pass after the deposit reached the standard. They said that the cash flow was not enough, and I was also asked to deposit another 500,000 for cash flow before I could withdraw. They did not inform it before. It said that I can withdraw immediately after reaching the requirements. I feel I was cheated.