I could not attend a telephonic interview since I was in a driving class when they called. I have since sent them an email apologizing and provided a better time at which she could call me (at their request). It has been 3 days and they still have not called me. How should I politely remind them?
Call the person who had called you for the telephone interview. There is a fair probability that the person might not have come across your apology or hasn't read it for some reason.
Calling the interviewer in person, apologising for the mistake and explaining your situation might be a better choice than sending an email and waiting for the answer. If your position and the reason for not receiving the call are explained politely in person on the call there is a fair chance for you, I believe.
It may possible that position is filled or she forgot to call you or she did not read your apology mail by mistake.
So what you can do is call her directly and tell little bit your introduction so she can recall things that Yes this is guy to whom I called for interview then you apologize if require. I think she will definitely set interview timing for you and will take interview if position still available.
In my own experience, I once missed the call from my soon-to-be employer. I checked my phone 15 minutes after they called. I immediately called them back and apologized. He was cool with it and then we had a good discussion. I would say do not hesitate, if you can call them it would also show you are genuinely interested and also consider calling them back which is always a nice gesture. Go ahead and call them! Good Luck!