I would have called them on Dec 1st, and then again every 30 days.
U guys are paying 2ndary fees for a reason (usually $50-75), its THEIR job to respond to ur concerns.
When you interview on September, and you don't call back till March, it shows you aren't really interested in their school. They could have rejected you by now (and didn't), so this means they might be somewhat interested in you