As far as I can tell, there are (2) reasons bittrex may not be responding:

(#1) They are waiting for an answer that depends on something else*
(#2) They literally don't give a fuck about you.

* I don't have any evidence of #1, just speculation

- Lack of staff or amount of tickets is not the problem.

Certain people can get responses to a ticket multiple times a day, or every day, back to back - while (clearly) others do not get any priority.

If you're not getting responded to, they're intentionally not responding. If you haven't had any response at all, or over 30 days, you're probably fucked.

It's possible who they sleep with will hold off the cavalry for a while, but that will not last forever. They'll have more than enough to fight it though.