DStv nothing but broken promises

I previously posted a complaint that DStv have been overcharging me since December on a contract for an Ultra Decoder. To my delight I heard back from them on 19th June. Andile informed me that my troubles are over and my account will be rectified. I couldn't believe my luck. Unfortunately nothing has happened and he appears to have disappeared like all the other call centre operatives. How on earth do you solve a problem with this company?