Binance used wrong exchange rate

Sorry if my English is dangerous. As we speak I bought usdt utilizing visa. I was presupposed to get no less than 190usdt but I only received 116 once I checked my historical past change price was 6016. Trade price of USD/MNT was 3597 once I bought it. But they used 6016. I contacted customer support they usually stored saying market worth moves continuously. But they used 40% greater fee. Now they stated wait and I don't know what to do