Where is my data going

I lodged a complain with telkom mobile for my data that goes missing without a trace or an explanation, today it became even worse I received a message that i was left with 499megs of data at 5:10 pm then at 6:18 pm i received another message stating that i have 98egs of data,The burning question is how is that possible because didn't touch my phone within that period.Sometimes I buy the daily data and it gets finished within 5 minutes just after pirchasing it the next minute its gone.This is frustrating i need to know what is happening to my data i'm sick and tired of being **********.