Yello more like good bye customers

Yet again another issue with my upgrade since my last report ***5. that issue was sorted only now to get a bill where I am being charged for data purchased even though there was money on the account and was reduced by. When I did the upgrade in September I distinctly requested it to be on top up, low and behold this is not the case. mailed the customer service on Monday where I got a response that the data charges is what was purchased via self service but as stated above there was money available on the phone which was reduced after the transaction now I am being billed again. when I responded that this is incorrect and I should be on top up I haven't heard a single thing!! this email correspondence was with Mmabatho Monyepau . I want this conract now sorted and an guarantee my next upgrade due December will be a cancellation instead!