Cannot get them to respond

I have totally run out of ideas of how to get MTN to respond to my request to confirm my contract cancellation. I cancelled my contract mid May and have been asking MTN to let me know that it has been done since, but I have not gotten a response. I am so glad to have left MTN, will never go back and encourage nobody to touch them. I have even left a reply on Hello Peter about this issue and no response. Can anybody advice what I need to do to get these people to respond.