Telkom a nightmare service provider

I recently tried out the free trial of Showmax via telkom ,it states on the ad that you cancel anytime immediately but there is no option to cancel,theres only an option to join and it's almost instantly. When I call Telkom to cancel the free trial within the trial period,they telling me they will effect cancellation after a month and they have even billed me subscription fees on it. I really dont understand telkom