Overcharged and not refunded

I had a data contract with Autopage and my contract ended after a 2 year contract I gave a months notice in Nov to have my contract cancelled in Dec. Autopage billed me for the month of Dec 2014 and January 2015, I called them numerously to have the amount refunded and to date had no feed back or refund for the overcharge. My service was cancelled in the beginning of Dec but the Money was taken out .