ME TOO! 
This is crazy! For the first few months using my jetpack, my usage was consistent with my usage when I was with Sprint. I monitor my usage on a regular basis. So you can image my surprise when I received two text messages in the middle of the night, 15 minutes apart telling me I was at 75% and the 90% of my 14 gig limit, just 17 days into my billing cycle. We had used just over 4 gig to this point, an average month. I contacted Verizon immediately. I was told that Verizon was having technical difficulties but she still put me through to a tech support person. The Tech gave me a song and dance about my data usage that did not match up with my data usage that was being reported on My Verizon, so I pushed the issue and called back. The customer service rep started an investigation on my behalf. When she called me several days later, I was informed that the usage was legit and it was my fault because I had left my jetpack on even when we were not using the internet and there must have been updates occurring. I was also told that nothing could be done until my next bill was issued. We run Linux and do not run ANY automatic updates. After turning off my jetpack for several days, my daughter turned it on for less than 30 minutes to check her email and blogs for her college class. It used in excess of .5 gig during this time. I will be taking my jetpack into the closest Verizon store to get checked out. If this is not resolved to my satisfaction, I will be eating the early cancelation charge and dropping Verizon. I would rather pay a little more through an internet satellite provider than be duped by a company unwilling to fix an obvious problem.
Increase Data Usage is very common, and if you want to increase your data you can sign up for Millenicolm 20GB for $89, plus inserting into a CradlePoint Cor or Peplink BR1 will be your solution to making sure your data used is that ..Your Data
Millenicom $89.99/mo 20GB 3G/4G Service (Requires Compatible Device) : 3Gstore.com
You are not alone here.
Data usage is a concept that eludes and confuses everyone. In truth there is no good way to go back and confirm that a device was defective or not since the actual data usage reports are owned and kept by VZW. VZW does not allow customers access to the real data reports so anything you challenge them with will be your word against theirs. Such is the nature of the business and capped data plans at this time for all service providers.
If you want a chance at defending your equipment then you must install and maintain data monitors. I do not have any recommendations for Linux machines (my favorite is Networx for Windows) but I'm sure someone has developed something for them. You can install monitors on your individual devices or on a router via firmware. Once you start monitoring there will likely be a plethora of data logs to review. Reviewing the actual logs is not going to be a user friendly experience.
Let it be known that data usage monitors are only for your own benefit. VZW does not acknowledge any data logs except for their own in disputes. IANAL but one can assume that personal data logs would not hold up in court should you decide to litigate either. If VZW says their equipment and logging are correct there isn't much you can do to prove them wrong and leverage a refund against them. All you can do is pay your bill otherwise VZW will send collections after you for voiding your contract.
The best defense continues to be to power down the Jetpack when it is not in use. Best of luck to you friend in your endeavors. If you learn anything new then please share with us so that we can assist others.
I can see by the posts on this site there are no solutions to an obvious problem with the Verizon Jetpack. My data usage says I have used over 15GBs! in a few hour period and I was only on the internet for about and hour and just the usual checking my email, bank statement, Facebook. My jetpack worked fine up until a two and a half months ago I have contacted Verizon a month ago about excessive data usage reporting. So far this month it says I have over 15G used! No way could it be. My browsing hasn't changed. My computer hasn't changed. I have not downloaded any music or movies for months and I shut off the automatic run on videos on Facebook. I've lived in the same house for 35 years. I shut my jetpack off when I'm done .. If I turn on the Jetpack. and check email and do some browsing,,.within half a day to a day I get a notice that says I've used almost 2 more GB of data!! This is insane. I haven't watched anything on Netflix since last April or May and even then I didn't have any overages. This is a new problem. I took my Jetpack in to our local Verizon Store and all he could do was confirm the data usage. The lady from online support who chatted with me last month said she would back charge to the cheaper plan for a month and then drop it the next month, but now my account shows I'm on a 14 GB plan (use to be 10 then she put it at 12 supposedly for one month..so don't know how in the heck it's now at 14) and it is saying I'm over my data usage. Right now I'm using my phone hotspot. I do not have overages being reported when I use this connection. I also have used my daughters hotspot and NO problem. Face it , to whatever Verizon Tech may be reading this... The problem is there's a bug with the Jetpack 4g or a problem with it's data reporting. I don't believe a large corporation would try to dishonestly upcharge data. I used the old Jetpack in 2011 and 2012 and NEVER had an overage problem. I updated to this new one last November and didn't have a problem until about 2 months ago. I'm an older senior and this is a big problem on a fixed income. My internet usage is about the same as it's been for the past decade. That's why I called Verizon about this problem. I thought maybe the account had been hacked somehow and someone was piggy backing on my device but with the postings on this site and others I see it's a Verizon Jetpack problem! NO ONE wants to Help. The replies I get from Verizon is " Well, this is what the data report says, so you must be using it somehow, with updates or background programs etc. " When NOTHING has changed on my end and it doesn't happen on other WiFi equipment it's obvious this is a Verizon Jetpack problem.. I am just not going to use my Jetpack anymore and believe when I say it will NOT be recommended to anyone we know, not that that will make a dent in anyones life at Verizon, and I use to think it was really a great tool for traveling etc. My husband and I do have the contract with Verizon and will run it out but this has been a really bad experience. BTW..I only hook this up to our computer at home or when we use the tablet up at our cabin,.so only one device at a time and no big downloads.
ME TOO!
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