Forcefully holding my profits

I have spent a significant amount of time in the Demo environment, but I have also put in some money into the live environment. I have so far lost about 250k which I initially attributed to my inexperience. However, i had an exchange with one of their support staffer/ broker who after a successful series of trades, I requested to withdraw my profits. I then continued to trade and ended up with a Margin call. They immediately took funds out of the pending withdrawal which had been requested two days prior and refused to release any of my capital after that.