Verizon Charges for Cancelled Service

I cancelled Verizon in the middle of my cycle. When I talked to the customer service I made sure they are clear that I do NOT want FIOS anymore but they charged me for the rest of the cycle anyway. How do I get my money back? I have called the customer service multiple times. The last time I called the lady told me she would resolve the issue and she would call me back, but she never did!!