VODACOM MISTAKE - I PAY FOR MISTAKE

I have a business account with vodacom on Cell number ********** 074 which was always a 'You choose flexi 350' account. Nashiem Abdul phoned me in 2017 Dec and asked if i would like to upgrade my contract, I said NO and that I would like to stay on the exact same contract. Nashiem changed the contract to a open line by mistake. I received my first bill on Dec 2017 and the amount was R 467.50 and R 1026.09 for Jan 2018. This is more than R700 more than what i CAN afford. I phoned Nashiem on 5 Jan at 12h00 and he explained that it was HIS mistake and that he would fix it and it would reflect on my account for Feb 2018. It did not reflect correct on my account in Feb, needless to say i phone Nashiem again, actually several calls and 6 MONTHS later my account was only fixed, after Nashiem promised every month that it will reflect correct the next month. I chose this 'You choose flexi' account because i have the funds to pay for it, I DO NOT HAVE FUNDS FOR AN OPEN LINE, and this mistake of Nashiem cost me R 3274.77 extra over a period of 6 months. I am now in debt as i had to make a personal loan to pay for this extra monthly expense.I spoke to Janica in Vodacom Witbank Higland mews in person to help with this urgent issue. I also spoke to Nosisi on 20/07/2018 at 13h00 Ref A2/AZ4K/4Q2YP and she said she will help me to be refunded for the extra R 3274.77 that i paid because of VODACOM's mistake. To date, I have not received any feedback. I would like a VODACOM to help me with this refund that i urgently need back to be able to pay off my other debt that i made because of a mistake that they made.