Installer given authority on my dstv account

DSTV installer name Peter came to my house to install dish and refused to install extra view cable as agreed with Makro Polokwane sales person (Dimakatso). I then found someone else to install the cable for me at a lower price and i was shocked when i called Multichoice to activate this service and they told me that i owe about R30 something rand. When i questioned they said the installer called to activate this service so my question is why is the installer given authority to change the financial state of my account. He did not even install the extra view cable and yet i'm being charged for something that i was not even using at the time. So now since the dstv vouchers have our confidential information, isn't Multichoice suppose to ensure that our information stay confidential? And that any financial changes have to be authorized by the account holder? I have been a Multichoice customer for a long time and i'm deeply disappointed at such a low level of service.<br> Calls reference numbers - *** and ***