1gig gone in 4 days?

this is one of the most ridiculous networks in this world,I buy 100mb of data every 3hours and it finishes so quickly,I bought 1 gig and it was finished within 4 days,its overcharging us and when I have airtime + bonus airtime and data,it usually takes up all my real airtime and data at the sametime ,Its a ridiculous network and I have been overcharged,surely I spent R500 worth of airtime in a month