Billing after my request to Close

i have emailed the customer service department in January 2015 to advise me on how to cancel my second conract ***) and migrate it to prepaid. they advised me to pay an amount of R390. -. the next month i paid a double payment as they billed me for the currently month. so i paid the R800 then asked them to migrate to prepaid. I asked to consultant to confirm with me the amount that will be debited and advised it will only be the main contract number ***. March 2015 i received a statement that i have been billed for both cellphones R768 or something, now for the past month 2 weeks I'm trying to contact the call centre each time i select the option to speak to a consultant the line drops. so how do i cancel my contract? so I'm going to be billed to thy kingdom come?. i just want my contracts to be settled so that i can change service providers. Pathetic Service experienced