OK, I am not saying that there is or is not a problem with Verizon, however I run 3 web servers and I have software running that detects attempts by remote computers to access them. Every day, I have hundreds of new IP addresses that are attempting to gain access and my firewall blocks them. The data I get from the software does a reverse lookup on the IP address and I can see that they are all regular joe computers spread across the world.
What in fact they are, are trojan attacked computers and laptops that are running programs that constantly probe the web servers for loopholes.
One of the servers passwords was discovered (it wasn't a very strong one) and in a matter of days, 18 million emails were sent from it. I'm still cleaning up the mess.
In that situation, laptops and desktops would have been churning out data that in most cases would not be noticed - Cable Internet and DSL users don't typically monitor bandwidth. However in the case of Mobile Internet, if this happens then all of a sudden you find the costs running away from you and unfortunately the providers don't cut you off at the limit - they just charge you for the overuse.
So do make sure that your laptop isn't compromised with a Trojan Virus.
There are also bandwidth monitoring tools available so you can see what is happening in real time.