airtime billing

I am very angry its not the first time this is happening waking up to 0.00 airtime even if I stil have data to cater for internet browsing. I had R14.00 airtime when I slept with enough data the next thing in the morning um credited with mtn to mtn airtime which you get when I use certain amount of airtime when I query they tell me if im on Facebook and I get whatsapp msg then whatsapp is billed from airtime as Facebook will reserve all the data for itself. To thinkin haven't even received any whatsapp message today. This is always happen in I want my airtime back please cause its funny that when I don't have airtime and have data only I am able to use all the applications at the same time.