Verizon Wireless Data usage overage scam Nationwide

I've been a Verizonwireless customer for many years and had a 3G hotspot for a couple of years and upgraded to 4G when it became available around 2010. My data useage was always low even though there were 2 computers and one Ipad sharing the data. In 2012 we upgraded to Iphones and a newer 4G hotspot with a 10gigabyte plan. From August 2012 until about July 2013 the data usage was on average about 5 to 7Gb. In about August of 2014 my data usage jumped to 12 gb with no change in activity or added devices. I spent about 3 hours on the phone with one of there techs trying to figure it out but to no avail and the tech told me he would keep an eye on it and call me back in one week to review it again, well that never happened. The following month the same thing happened so I called and connected to a different tech person and spent two to three hours trying to figure this out and he suggested it could be one of the computers updating and to turn a different one off each night to see if it solves the problem. I did that but couldn't identify a proble.  The following month the same problem again, so I called and talked to a third technical support person and spent a couple of hours and she couldn't figure it out either.  For the last couple of months, all of our devices have been turned off at night including the Hotspot itself and there has been data usage showing up on the data usage breakdown for hours that no one could have possible been using data.  I have reached the conclusion that is isn't my usage that is the problem, it is Verizon and it's crediting data usage and billing that is the problem.