This is a real case happened with my friend on bittrex,
He's got hacked 10k USD, withdrew in BTC to another account. He cried it to the support team and guess what??? They replied with a sorry email including an activity report of his account.
SO BE CAREFUL GUYS...
Did he have 2fa enabled? It is not Bittrex fault your friend is a noob and doesnt know how to choose a good password or surf the internet safe and regarding the other accusations i never had any problem with Bittrex but i believe the people talking about their issues. Good luck