Can you give us more details? There are a few possible reasons why this happened.
1. You copy-pasted the wrong address.
2. You have some malware in your device whereas they replace the address that you copy-paste(though I think this malware is more for bitcoin and eth).
3. They sent the coins from your deposit address to their cold storage.
4. They really got hacked.
If you deposited a significant amount(probably not, as you said you deposted just to test the exchange), and they're not replying to your complaints, I really suggest pushing this to Reddit r/cryptocurrency. Sometimes you just need to give them negative publicity for them to actually do something regarding your complaints.
https://reddit.com/r/cryptocurrency