MTN SA falsely selling their products to get clients

MTN SA has now resorted to false advertising to get clients. I was sold a month to month contract, to which I was informed is of convenience because it allows for cancellations anytime at no cost. I’ve called over 5 times to cancel but have been told this is a 2year contract and I have to pay a cancellation fee to have it cancelled. Why must I pay a cancellation fee when I was sold the contract under a month to month ‘pretense’?