Hello, I have had the phone a month and used 2.34 GB. I watch Netflix on the television via the wifi. On the phone I do phone calls, watch NECN news, Facebook, play chess, watch news on CNN, watch some Utube videos and the like. I was told that the TV on Netflix does not count toward the phone usage. What is using so much?
Check the mobile data in your phone's settings. It'll show which apps have been using data.
To conserve data, I keep mobile data disabled unless I need to use it. I also have background data turned off on all apps that use it. This wouldn't be a good option for those who need to continuously monitor things such as security cameras, doorbells, etc.
My phone (LG X Charge) has a setting in Advanced Wi-Fi to switch automatically to mobile data when Internet unavailable via Wi-Fi. I also keep that turned off.