What can I do when a employer won't give me a separation letter? Or who can I call? I'm supposed to…

What can I do when a employer won't give me a separation letter? Or who can I call? I'm supposed to have it this week. And I've been calling and going up there for a while. All they say is I'm going to give my manager your number and he'll call you. And he hasn't.

This happened while i was working there with another girl she came up there everyday for weeks. Idk if she ever got it.