Binance used wrong exchange rate

Sorry if my English is dangerous. At this time I bought usdt utilizing visa. I was presupposed to get a minimum of 190usdt however I only obtained 116 once I checked my historical past change price was 6016. Trade price of USD/MNT was 3597 once I bought it. However they used 6016. I contacted customer support they usually stored saying market worth moves continuously. But they used 40% greater price. Now they stated wait and I don't know what to do