Every pool gets people complaining about not getting back what they paid into NiceHash.
The pool is working: https://ethereum.miningpoolhub.com/index.php?page=statistics&action=blocks

If you want certainty about how much Ethereum you will get back, you should use an exchange.

You have all the information about your shares the whole time it was mining:
https://ethereum.miningpoolhub.com/index.php?page=dashboard