Has anyone ever tested data usage? I have 30 gig and go over every month. I don’t believe the calculations are correct. I’m getting ripped off. Wifi at home And office all day and night .
I track my data usage fairly closely. Watching videos or having background video ads (that you don't see) will eat up a lot of your data when on-line. Basically they are robbing you of data, so try using a free ad blocker with your browser. The other thing you might try is changing your wifi/modem or router password by typing 192.168.0.1 in the address bar and logging in. Google your device model for more detail. Not that I am paranoid, but if someone else has your wifi password, they can be using your wifi signal if they are close to you.
All depends on the app, but even when you are not directly using the app, many apps (either on purpose, or by a bug, etc) can continually keep using data. I had this once, where had a web page open in safai, which was chaning adds (video adds) like every 30 seconds. I could literally watch my data going up and up. Force killed safari. It stopped.
If you have apps you dont use on anything BUT wifi (you would never use while out), you can usually go in and turn off cellular data for them, that they CANT run when cellular only.
As well, as mentioned, VIDEO can be a big killer, that people are not aware of. Sure your watching the video on whatever phone, which may be only whatever resolution. But if your watching a twitch stream, or youtube video, which say is in 4k. It will still stream to you in or close to that 4k, its just not displayed that high. Those videos will use up MUCH MORE data.