Overcharged for data never used

I received a bill of 11000 in march, and then 7000 in april, then 4000 and 3100 in june. I have been paying all these amounts even though they have been ridiculously high because super Vodacom simply suspends the customers number if not paid even if the bill does not make sense. I went to the branch beginning of June, they discovered that there was some data being used which made the bills this high. I hardly use the internet and at some point they say it shows i used 400 mb in one hour. This was taken up by the call centre for investigation, a month later i am still waiting and i must pay another high bill. Reference A1-x57M-TQR1D9. Please come back to me, i am supposed to be paying less than 2000 for this contract. It is so unfair.