Cell C and Disappearing Data

Hi all Cell C has a problem how they calculate your data usage I bought a Giga 200gig package on the 1st of June and I have been using it for seven months. If you take 200 gig and divide by 7 = 28.57 gig per month. I have check my local data monitor on my laptop and I have not come near to averaging 28.57 per month. I check on 26/01/2019 how much data is still left the ussd service recorded 5757.69mb or 5.7 gig. On my laptop monitor it says i have used just 1 gig but Cell C records that i have used 4 gig.

I don't experience this disappearing data problem with telkom