Poor service delivery and mistreating customers

I signed up for a month to month contract with CellC and the agreement was that I can cancel my contract anytime at no extra cost, now when I want to cancel my contract they tell me that I need to pay R1250 cancelation fee. And when I ask them why should I pay if I'm on a month to month contract, they say all month to month contracts have been changed into a fixed contract yet they never phoned me, text me neither did they email me. And again my data disappeared and when I call them they said I was on Facebook all night whereas I don't have Facebook installed on my phone. Again they overcharged me on my contract and when I call then they tell me to go to the store and at the store they tell me to call Cell C direct.