I am posting this here because I didn't have this problem until getting the S8+. I'm assuming it has to do with the phone as much as it does the app. Facebook messenger went on a data binge yesterday and used 1.75 gigabytes of background data while my phone was not being used on my desk at work. I didn't know until I picked up my phone and had several messages from Verizon saying 25% data left, 10% data left, and then finally 0% data left. I looked in data usage under settings and identified the culprit as Messenger. I called Verizon and they took care of me and refunded me 15 dollars for the overage data and gave me a free gig of data burst. I uninstalled Messenger and reinstalled, thinking it was a fluke. I didn't want to block Messenger because I do most of my communicating with family through the app. Well, Messenger struck again this evening and used another .75 gigabytes of background data before I realized it and shut it down and uninstalled it. I notified facebook through one of their silly reporting messages. Has anyone else had this problem?