Incorrect Double Billing

I have been in contact with the call center for 3 weeks, me calling every second day. My query has been closed by Vodacom 3 times already and every time it’s because they claim not to find my proof of payments. I have 4 contacts with Vodacom and recently upgraded on 2 of them . Before upgrading I asked for settlement letters to settle the 2 so I can upgrade and only pay for new upgrade amount on the 2. I got the letters and paid and sent pop. The 28 September amount deducted was correct, the problem started in October in which I was double billed for old and new upgrade. The 2 numbers I upgraded are ********** 636 and ********** 534. I’ve been also charged for a promo data which was supposed to send free on the 063772 number. Again the November invoice is showing all the incorrect amounts that I have querying. Please Please help