The black platformGXCM scams me, and my funds cannot be withdrawn!

I made a deposit and investment on GXCM. After I made a profit, I wanted to withdraw the funds in my account. However, it took more than ten days for the withdrawal application to be approved. I asked the customer service, he asked for a 500 yuan certification fee on the grounds that the UnionPay card information was wrong. After I paid the authentication fee, I applied for cash withdrawal again. This time, the platform used UnionPay's monitoring and interception as an excuse to demand 20% personal income tax to continue with cash withdrawal.