Month to Month contract changed to 24months contract without my permission

I called Cell C on the 11 March 2022 to cancel my month to month contract which I signed up for but cell C just informed me that the month to month contract I signed for has now magically been changed to a 24 month contract, and if I want to terminate my contract I have to pay a cancellation fee. When I asked who had changed my contract term I was told it was Cell C Directors. I was told to send an email to *** which I did and they did not bother to revert back to me.