I finally took a close look at my CenturyLink bill and saw that they had been charging me for local calls even though my plan includes local calls unlimited. After dealing with two customer service reps (one disappeared on the call) the following was determined. The local calls I had made were coded as DD in their system. This means the call was made with the support of calling #411 to get the number and be transferred to it. Before the first Rep was disconnected she indicated they would go back only 12 months to credit my account for the erroneous charges. The second Rep said I would only be credited for 6 months of their mistakes. She said there would be an investigation that would take up to two months. Check your bill!