Cell C glitch paying extra!!!

Was just informed that they will be billing me extra from this month- when I phoned to Enquire they informed me that “I “ had requested a monthly recurring voice bundle. Which I had NOT!!! I didn’t even know something like that existed! But even though I then said I want it canceled I’m still required to pay for it this month! It must be a system glitch or something- my husband was also informed that he’ll be paying more from this month!!! This is *********!!! Yet how do I stop them just withdrawing whatever amount they want from my account!!!