Upgraded without being told that I am upgraded

In the beginning of November I called CellC to cancel one of my numbers and I was advice that I can only do so at the beggining of Jan 2020 to avoid any cancellation charges. The consultant who was assisting me (Mpho) told me that since I have been a good customer CellC is going to change my package on the other contract that I have with them from 5GB to 10GB at R149 per month (I was paying R215 on 5GB). I asked him if there are going to be no extra charges and he said no. I only descovered that this Cell C consultant decided to upgrade me to a 24 months contract without even informing me. I have only discovered recently that he changed me to an open contract without even informing me. I was initially on Top-up since this contract is used by my son. I am really so angry with CellC and i am going to end all of my business with them since they are not trustworthy and they are ******. How can you upgrade someone without reading to them the new terms and conditions, without informing them that the new package is now postpaid, without explaining this will be a new contract and the new contract end date? I am so shocked of such a poor service from CellC. Now I am being charged extra. I had already paid for my 5 GB in November. They charged me a pro rata from the 9th of November-30th of November, without being informed of such. I only discovered all of this when I got my invoice. If it was explain to me that this is an upgrade I wouldn't have taken it. I would have rather opted for the Vodacom deal of 80 GB for R299. My reason for the call was to cancell not to do a contract upgrade. Stop being ****** Cell C.