None of your requests will probably be granted. And even sound a bit extreme, and lucky you got 50% off.
Hacked is not the right term but yes someone else may have either connected to your hotspot or have something large downloading on your computer.
IE netflix takes over 1 gb for video watched in hd.
If you either don't secure your hotspot with a password that you setup or don't use one strong enough that is all on you and has nothing to do with Verizon. Not their fault at all.
Also they provide tools to monitor how much data is going thru the service per month that you can easily check on and see if going over.
As of right now there also no laws againts the hacking of devices your failure or theirs that would make your carrier be liable no matter who it is.
Just properly secure your connection with a stronger password and be happy it wasn't more as easily could have been.
But they will not refund your purchase charge or let you out ETF free as it was not their fault that this occured.