Disgusted in Telkom

I am disgusted in Telkoms service. My contract has come to and end(finally) and I was called in the beginning of the week to ask what i would like to do.I told the man I do not want a contract, I just want my normal prepaid whereby if I need airtime etc I will purchase it myself. He promptly and disgustingly put the phone down in my ear. I called back and as bounced from one person to the next who refused to help me. I have emailed billing twice and again I am ignored. Now I receive a new invoice for an amount I did not approve because I explicitly stated I will not be renewing the contract. How can a company that was once good be so revolting and not listen to customers!