I have not encountered a situation like yours, so it is important to choose a good exchange, such as OKEX, HUOBI ect.
If we have seen how binance has been taking a action to the recent API hack on syscoin and the major exchange site give use the more guarantee for that. Remember the major exchange sites are giving back our money if there is a strange thing will be happening on the exchange site just like hacked case and any other case.