If you don't own the private key - you don't own the coin, it's as simple as that.
Store in your own wallet, and trade on decentralized exchanges (IDEX, etc - there are a lot more coming out, I believe binance are developing one).
I found it very risky to store your digital currencies in crypto exchanges because this entity is one of the best target by cybercriminals because they know what they can get inside of it.