Vodacom Unauthorized Upgrades

I have spent the last 7 months trying to find out from Vodacom who upgraded my kids phone contracts back in April when its my contracts and I was never contacted. I get passed from one person to another without resolving the issue. I get told they need to investigate and listen to recordings and then will revert to me in 72 hours. They never do. I'm now trying to just close the contracts to avoid another month of paying double their original contracts. I've tried closing my sons contract for the last 5 months!