Incorrectly Billed for months!

i had signed my wife up with v a towards the end of last year, v a was running a special, like 99 a month and i was given the opportunity to pay the vitality once off fee over 2 payments, 1 payments when we signed up and 1 towards the end of that month. we were informed that it will be debited from our account. last week my wife gets a call informing her that she is in arrears with v a for R600 something. which was strange as i had enough for more than a years subs,so i called them to sort it out, i was told that even though i have all my wives information and she is a dependant on my medical aid and vitality, that they will have to speak to her. as she is busy teaching the entire day&it is difficult for her to call i asked if they could give her a call, they sid no problem, i distinctly asked if the person who calls will be able to sort out the issue&she said yes. the agent calls her and tells her that she must pay the amount and that if she wants to query it then she must call another number. i checked her bank statement today & they have been billing her R599 every month and the reason the debit has been bouincing is because the funds are depleted, now billled R115 for no funds.