Shocking service

Telkom is probably the worst service provider I have encountered yet. We moved our line to a different property in December. In Jan they billed me for both lines at the old house and the new one. Called to query it and they said they will rectify it. February billing came same thing. Called again and they said they would rectify it. Received March account still showing incorrect billing and now i receive a LEGAL NOTICE that i am in arrears when they actually owe me money as we have overpaid because they were billing us for 2 lines. Try and call to query it again - They OFFLINE big surprise and they cannot call me back I must carry on calling them to see if they online. ITS RIDICULOUS and UNACCEPTABLE! I will be cancelling my contract ASAP!