I think it's unfortunate that USNA Admissions doesn't show up when they indicate they will. Tend to agree with the others that it's a staffing issue. USNA has moved more toward civilian folks in Admissions, and there are some real benefits to that approach. However, civil servants are paid for X hours of work per day. Most can't work OT without permission and getting paid for it. As for the military members of the Admission staff, there is a lot of turnover . Thus, my sense is that some of these calls are falling through the cracks. It shouldn't happen and is obviously discouraging to candidates with questions that cannot be answered by anyone else.
Keep persevering.
The OP's issue aside, as a general rule, there is more desire and expectation today for "hand-holding" than there was in the days before the Internet. When I was applying to grad school, I received an acceptance letter from my top school in early March. After that, I didn't hear from anyone at the school AT ALL for months. No call. No letter. No information on showing up (when, where), housing, etc. I actually pulled out the acceptance letter again just to make sure I hadn't misread it (not kidding). I finally received a "welcome" packet in late July for a mid-August start date. And I showed up and all was fine. That's just the way it was. It's different now -- I get it.