Data Disappearing

For the second time my data is disappearing, first on the 15 November my 1 G disappeared in a space of 15 minutes, now on the 12 I just loaded 100 MB it just disappeared in a space of 5 minutes after loading it. Telkom told me the first time they have to log a call and will take up to 9 days to resolve. I was not on any apps so I don't understand what is going on, my automatic backgrounds app refresh is off and so are my app updates. The last time I had this issues it had appeared that this was the problem, I'm not sure what excuse they are going to provide me with, what is worse is they refuse to pay me back my data. What are the possibilities that I would have used 1 G data in 5 minutes especially when I was not using any internet.