Data vanished after promise it would carry over

I had a 100GB pm contract with Cell C that comes to an end at the end of December 2020. At beggining of November 2020 I called in to say that I will not be renewing my contract so my last payment will be at the end of Dec. The Cell C agent whom i spoke to and processed my request told me that at the end of November 2020 my contract sim will turn into a prepaid line***) and assured me that whatever data will remain at end of November will carry over to the prepaid sim up to the end of December. Imagine my surprise when on the 1st of December all the data(over 50GB) that I had preserved for use in December just vanished. I called the Cell C call center and explained what had happened. The lady who attended to me said I could not get a carry over of my unused data as I had terminated my contract. I told her of the advice I had received from one of their own and asked her to retrieve the recording of my call at the begining of November. That's when she told me that the call had not been recorded and that nothing was gonna change, She then hung up on me just like that. Is this how things are like at Cell C where they just want you to sign on a contract but when you cancel on end of contract they are not courteous or considerate at all. Is this a case of the right hand not knowing what the left hand is doing at Cell C. Fellow citizens be warned when you are signing on at Cell C.