I mistakenly deposit my BTC to my BCC address. How can i get it back?
You will need to contact HitBTC and ask them to correct it. In theory they have the private keys and can recover these coins in a way similar to splitting Bcash and Bitcoin in the first place, but prudent security practices may make this difficult for them to do.

You might also want to contact the creators of BCash and point out to them how this decision to use addresses which are indistinguishable from Bitcoin has caused you problems. This was a conscious choice on their part and has resulted in funds losses for a number of people, just as Litcoin's similar mistake years ago with P2SH addresses caused.