Charging me to cancel my contract, but I have a month-to-month contract and I am giving a month's notice.

I do not recommend taking any kind of contract with Cell C. I joined them on the condition that my contract would be on a month-to-month basis, only in the condition. Now that I want to cancel my contract, and give them the one month's notice as per the conditions I agreed to, they inform me that their conditions changed in November last year enforcing an early cancellation fee. 1) I have a month-to-month contract and I am giving one month's notice, how can this attract an early cancellation fee? 2)The first I heard of this cancellation fee is when I called them. I have been passed from person to person, being told no agent can assist me and that the only thing I can do is send an email to customer care. I did this, received a message informing me that I would be contacted within 2 days. Only to receive an SMS the next day informing me of their changed policy from November and another SMS telling me my case is resolved. My complaint is far from resolved. When I called to ask how I can resolve this, I was told I should just pay the cancellation fee. I ask again, how can there be an early cancellation fee on a month-to-month contract. The agent then says that that option no longer exists, except it is still advertised on their website. Do not do business with Cell C.