complicated monitoring of data usage

Will have to take screenshots to prove how complicated it is to monitor data usage on vodacom app , if i have contract 20 gb night , 20 gb day , 10 gb day bonus , why can 10 gb day not run to nil before taking off 20 gb day , does up to a point then "everything changes" so confusing for us customers who need "things" as simple as possible , starts showing eg 20 gb day 18.00 left and 10 gb day bonus 3.00 left at the same time , many of us rely on data monitoring to be as simple as possible and have high data usage so need to know at all times exactly how much left at what time, can't have screens changing one day to the next