Has anyone else had issues with their iPhone using an insane amount of data?

What kind of apps and things do you have on your device? Did you restore this device from an older device? Have you tried restoring this device as new and not adding any content back to it and testing it? What kind of things are showing as using data when you go to Settings>General>Cellular. The apps listed there will show how much data they have used over the period since the list was last reset.

CrazyiPhoneData wrote:

A few months ago, I upgraded to the iPhone 6 Plus. Since upgrading I have been burning through an insane amount of data. I am using my phone no differently than I had used my phones in the past. Verizon was able to look up my usage and see abnormal usage, like my phone using 2.5 GB of data in one split second. They had no explanation for why this is happening, so they tried switching out my SIM card with a new one. But that apparently did not work as I am still having this problem. I can't continue on having $600-$800 phone bills because of crazy data charges. Does anyone have ANY suggestions for what might be causing this problem? I am contemplating a trip to the Apple Store to have the Genius's at the Genius Bar take a look at it.

It is not possible to use 2.5GB of data in a split second. Even Verizon's network at its best can't get past 20 Mbps, which translates to 2 MB in a second. So if that is literally what they said, their billing system is seriously screwed up. And Verizon's wired FiOS network is only 50 Mbps, or 5 MB in a "split second. And even the fastest network in the world, Google's gigabit fiber, couldn't push that much data in a second.

At least temporarily, I would go to Settings and shut of Cellular Data until it's resolved to prevent charges.

But none of that explains how it could use 2.5GB in less than a second. In rough numbers 2.5 GB is 25 Gbits. At 20 Mbps it would take a minimum of 20 minutes to use that much data. And Verizon's network is far slower than 20 MBbps most of the time.

CrazyiPhoneData wrote:

I Checked through all the app data in the cellular settings. The App Storr showed the most used data at 483 MB. I Went through apps like Facebook and Instagram and made sure that the Autoplay for videos is turned off. Ive done everything I know to do to limit the data usage. When I got this phone I set it up as a new phone, alsi I have reset the phone hoping that would help.

Well, 483MB of data is no where near a $600-$800 phone bill, nor 2.5GB worth of data. Given what you say you witness on the phone and what you are saying from Verizon, something doesn't seem to match. But, it is hard to say who is being honest about this. I guess I would first ask when you reset the counter on your phone to track your data. Remember, your phone bill has a billing cycle, so you would have to try and match that to see how close your phone estimate is to what Verizon reports.

What other troubleshooting have you done on the phone? Have you restored it? Have you tried it without any other applications installed?

You are correct in saying something isn't right. Especially considering your devices are reporting at most 11GB of data and Verizon is claiming 21GB. While at times users can see a jump in data, this one is way out of line.