Vodacom *****ing from me

I bought an airtime to buy a 10gig of data because it was on red hot offer. I did bought a 10gig the next thing vodacom sents me a montly statement including the amount of 10gig that I have bought with my airtime. I called vodacom spoke to the lady, she told me by clicking on the red hot offer it means I am activating a reoccurring data. I asked them to cancel that and she was unable to do so. I called again and the phone was picked up by the guy and told me he will deactivate that option on my behalf. That was in June. Today they sending me the invoice again saying I owe them 998 they will debit my account with that amount. Called them again they told me I have reactivated that red hot offer, I told them when was it done coz last time I checked I'm not using data from vodacom because their network is unpredictable and it's very slow. So I will take it up with my clientele laws.