MTN is a *****. THEY DNT WANT TO CANCEL MY CONTRACT. I DNT WANT TO UPGRADE!!!!!!!!!

I have called a countless times to cancel my account. The last time I called to cancel the consultant re-assures me that it was cancelled but I keep getting messages about an upgrade and a billing! Please stop with your theft MTN. I no longer require your service and my contract has ended. I DO NOT WANT TO UPGRADE. Please, please cancel