The Cryptopia hack is Exactly why you're warned never to mine towards an exchange, but people keep doing it. Not feeling sorry for the blokes that did that, serves them right.
I have had issues on Crryptopia with the withdraws, and then when they changed to CN8, there was a window in which I was able to move all my Xcash on Cryptopia to my wallet, and did that because they had a massive amount of issues already with the withdrawals before that point.
After evacuating my coins back to my wallet I exclusively used Stex to buy Xcash (never sold any!). I just buy and evacuate immediately; no time to feel butthurt due to the fees....