Telkom billing

I received a bill from Telkom that had additional R1300 claiming is for 3gb data that was used on one of my Telkom numbers. This was not the first time Telkom has charged me stating that its data or airtime that was used extra on my number while I had made all my numbers limit as zero since u have already minutes and data given to me monthly. I logged a complaint but wasn’t helped since they said data was used meanwhile the same number in question gets loaded 3gb monthly on its package.