Double charged

I cancelled my phone in November last year in KZN, and had the line transferred to the Free State In February, this year. The day after we moved in we had the new number and line transferred which was impressive. What i wasn't impressed with I got billed for the KZN and the Free State line. At the same time someone had used my KZN line and we weren't even there. I finally got the line cancelled but I get the bill every month for the February KZN line! I have phoned nearly very month but none can help, they just say the will create a dispute and that's the last I hear. The Telkom office in Bethlehem said I shouldn't have been charged that and were very helpful but that office has been closed. Because the overcharged amount is still on the bill I get charged interest every month! PA Hansen