I have Android and am having the same problem. I have a 4g plan, which has always been more than adequate--the most I have ever used for any month was about 2.5g. But for the last 3 billing periods, my data usage has spiked to a little over 4g--just enough to ding me for an overage charge. I have not been doing anything more with my phone than I ever have. In addition, I have set my phone to connect to WiFi whenever possible (which is about 14 hours a day). I have talked to reps here, and even gone to the Verizon store to get help, but all I hear is "bump up your data plan." There is absolutely no reason why I should have to pay more when I'm using the phone less. I have looked at the data analysis, and what I see is that I get slammed the second I get out if WiFi range. What is that about? I have done everything possible to try to fix this.
This is not acceptable.