City Power Accounts Ignores mails and are rude

I have been trying to resolve an exorbitant account that we received from City power out of the blue after installing the smart meter of over R20 000.00 for account ***. When I initially phoned and inquired I was told to ignore it was an audit and we must pay the amount sent via sms (have recording). When I received the bill the 2nd time I phoned and was told we had not paid our electricity from April 2014 to July 2015 and then was put on hold for 30 minutes (have recording). I've mailed through proof that we have paid and my husband has sent mails and still despite the bill being adjusted to a lower amount we are getting sms to advise we owe over R20 000.00 as well as we are receiving letters of demand and threats to cut our power and to date no one has responded to any of our mails to log that we are contesting the account, not even when I phoned in. There is numerous people in our complex and complexes in the area with the same issue since the smart meters were installed and in addition to this problem our monthly bill has almost doubled since the meter was installed.