Frustrated with Med Provider's Refill Policy

I'm stuck in such a frustrating loop with my med provider- I contacted them for a refill on a med I'm about to run out of, but they refuse to refill me because I need to be seen(which I completely understand), but they don't have any times for an appointment that works with my work schedule and trying to get a time that may work just gets declined. I'm so frustrated- I work as a teaching assistant, I can't usually drop out of a classroom to take an appointment and I don't get home til maybe 530pm, and its hard to take a call in the car. I'm just stressed and really don't want the answer to be switching providers again as I've been through several.