Data disappearing

For the last 3 month my bill has been incorrect. I had a bill of over R7000 in February, R4000 of which was for out of bundle data usage. After querying this a credit was issued. In March there was over R1500 for out of bundle usage. The 10 gig I get on the 1st was gone in the first few days. Over and over this to avoid another R4000 bill I kept loading data bundles which was over 10 gig.

I loaded a 2 gig on one afternoon and within 20 mins got the first message saying I have 500 mb left. After numerous service logs and calls I am told the bill and usage is correct.

So in one month I use over 20 gig for WhatsApp and email. I don’t ever download or watch movies. ???

At the beginning of the month we got fiber and have only been using the fiber on the phone and therefore had data carried over from March but the consultant tells me I have R1300 out of bundle usage. How can I have data roll over to new month and out of bundle usage???

Don’t know what else to do as the call Centre can not help