Unable to withdraw funds and asking for more amt

before 1st withdrawal, i asked about the entire charges and all, but was informed no charges, at 1st withdrawal request, ask me deposit what i have inside to verify my capital. after doing so, i deposit more and after earning requested to with all USDT44138. but was told due to 3rd party credited to my account, they suspect AML and request me to pay back USDT20000 via deposit. i did so and request to withdraw my fund of USDT44138. but now they say that i need to pay bank charge of 25% due to exchange rate charge by bank. Till date, I was requested to pay more and more but still unable to withdraw my funds.