I've recently signed up with the free RingPlus plan which allocates almost no mobile data. I'd like to find an app that allows me to control mobile data usage of my apps so that there are no surprises. I'm already using My Data Manager which tracks overall data usage and includes some alarms. I'm now interested in adding an app that allows me to turn on or off mobile data and perhaps regulate it on an app-by-app basis. Naturally, I'll use WiFi whenever it's available. Suggestions appreciated.