Vodacom taking money out of account just like they want to

I have been having problems with vodacoms deductions for about two years know, every time they make a mistake and i end up paying for it, I upgraded my Phone October 2017 and i confirmed with consultant what will the premium be that will be deducted and he confirmed R610.00, first premium went off of R 920.00, i called the call center and the could not tell my why, I then call the consultant who assisted with the upgrade and he informed me it was because of premature upgrade, something he forgot to inform me about at upgrade stage, he then said December will be last payment and this went on until January, i called Vodacom to find out the cancellation process as i had enough of it, but then decided against that, to my surprise Vodacom deducted R 7 904.45 of my account, i call to find out why and they said it is for equipment, is there anybody that can help with this useless service i am receiving from Vodacom