Cell C cant do a simple upgrade

Spoke to 5 people at the Cell C call centre and not one could assist me. My contract comes up for the end of its term. I received a call for an upgrade and accepted it. Got the device and then tried to activate it only to find out that the information given to me was incorrect. I requested for the device to be collected and the upgrade cancelled. Device was collected and I had to call and follow up to get feedback. I decided to give Cell C another change as I needed a WiFi Router. Promises were made to call me back to process this and again I had to call back and follow up. Today I called and spoke to an know it all call centre agent. Told her that I wanted to cancel my contract and the upgrade and if I don't get confirmation that it's cancelled today, I was going on Hello Peter. All she said was there is no need for...threats. Clearly she does not even care about the Cell C brand to make comments like this (Amelia Zulu). Can someone get back to me on this case. Reference numbers - *** / *** / obs153020. People I spoke to...Paula, Sharon, Lebogang Komani and Sello Mokgata. Asked for a supervisor but clearly I am not important enough to get that from Kriyaan Na