Complaint Review: Verizon

We have gone from never exceeding our 4 GB data usage on our Verizon plan 3 months ago to now exceeding every month, with our most recent bill charging $90 for overage.  When this started happening, I called Verizon and spoke with several people, in addition to visiting our local store and they cannot determine why we are suddenly going over our alloted usage every month.  Their only suggestion was that I should uplug the modem at night so that companies cannot go onto our computers and do upgrades during the night. I have been doing so, with the result being that we now have $90 overage charge.

Does anyone know what is happening - does Verizon suddenly have a new way of computing your usage each month or where is this overage coming from.  We are doing nothing different than we were before this began, using the same equipment as before.

Any ideas out there - Verizon certainly has been no help so far!