CELL C IS ROBBING ME OF MY DAY DATA

I bought a Data bundle 50gig/50gig day for R500 To my surprise cell c Is using my day data for during the night as I using it after 12 in the evening as I am working that time. As my night data is still on 50 gig and my day data is nearly depleted within a month. It just shows you how this company is robbing their customers