Charged for Data that was not received

On the 14th of every month i receive 50min, 50 sms and 100mb data, on the 14 Feb i did not receive the 100mb but when i was billed, i was charged for the 100mb data, i have been talking to mtn customer care since February but upto now i still havent received the data and now after about 8 calls to mtn they say that i have received to 100mb, i have been purchasing data on an addoc basis up to now and i am currently waiting for a validation report from mtn showing that i received the 100mb data.