This app was mentioned in 2 comments, with an average of 1.00 upvote
you should go download Preserve Data in google play. I found it today and it helps you preserve your data. Notifying you whenever youre on wifi & cellular data together https://play.google.com/store/apps/details?id=com.as.data.cellulardata
This app preserve data just came out today on android and helps make sure you are notified whenever your data is on or off with your wifi so you'll know to turn your data on or off. You dont want to waste data while youre connected to wifi. https://play.google.com/store/apps/details?id=com.as.data.cellulardata