iOS 9 is out and if you have it on your iPhone there's one setting that you might want to change right away. It's supposed to help speed up your Internet, but it could be costing you data without you knowing about it.
It's not a bug or hack this time. It's all due to one sneaky little feature that is actually meant to help you with your day-to-day Internet use.
The feature is called Wi-Fi Assist and it works by patching weak Internet connection by switching between Wi-Fi and cellular data. This prevents annoying lagging when uploading pages and watching videos but it can also do a number on your data usage.
Wi-Fi Assist is automatically turned on when you update your iPhone to iOS 9. That means it may be charging you right now without you having to turn on anything. According to Quartz, an iPhone owner that uses about 1 gigabyte a month can eat up 3 GB within the same time frame.
To disable this feature, go to your main Settings page>>Cellular. Scroll down until you see Wi-Fi Assist and toggle off.
Important: This feature is only included on the most recent Apple operating system, iOS 9. If you have iOS 8 or lower, you will not see the Wi-Fi Assist option under Cellular.
Now, you'll be free from unannounced data charges and bills that are through the roof.