Do you turn mobile data off while on wifi? Some phones are capable of using both at the same time in order to prevent a delay - not sure the 4s does, but worth looking into wifi settings. Also make sure updates don't go automatically or if they do only when connected to wifi.
Keep in mind if you are thinking you're using data at the same time as wifi because your bill shows you used data at 12pm and you know you were at home, data gets reported later from when you used it. That data could have been used in the last few hours.
I would be heartbroken if you left Verizon Wireless. I want to do everything I can to keep you in the family for many more years to come. I know that I use my data a ton, so knowing where that data goes is super important to staying under my monthly limit. What do you normally like to do on your phone? How do you normally monitor your data usage each month? I look forward to the opportunity to help.
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