High bill with unusual calls and texts from non-functioning numbers?

Question

We have a family share plan with 3 phones, one phone for my husband and two phones for our employees.  Our usual phone bill runs around $150.  Our last bill was over $600, the majority charges being on one of our employee's lines.  This particular employee has been with us for over 10 years, and has always been extremely trustworthy and very frugal in his usage of his phone to make personal calls (very infrequent and always less than 5 minutes in duration, unless made during the free nights and weekends timeframe).  Our latest bill showed over 1,000 texts to/from his phone, as well as over 3,000 peak calling minutes (both to/from his phone) alone.  Many of the peak calls are lengthy in duration (30+ minutes, up to 120 minutes).  I realize this post is long, so will divide it into headings so that it makes more sense:
Information on usage:
Our employee insists that he did not make these calls and texts (he does not even know how to text), and what is odd about the numbers that appear on the detail (both text and voice) is that they fit into one of two categories:
1.  There are calls to two particular non-local area code numbers (and possibly bogus, as they have area codes 523 and 352(?)).  When I call the two numbers, I get the following messages:
From my landline:  When called from my landline, adding a "1" before the 10 digit number, I get the recording stating that "your number cannot be completed as dialed, please check the number and dial again"
From a cell number- When calling from my own VZW phone (on separate account from husband's), I get a VZW message that the number "has been changed, disconnected or is no longer in service"
2. They are local area code numbers, but when I call the number, I get a recording asking me to enter my pin number (in other words, they are numbers that cannot receive incoming calls, but according to our bill, have not only made calls to our employee's phone, but also received calls.  I have done an online lookup on these numbers and they are all cell phones.
3.  When I have tried to text the non-local numbers from my VZW phone, I get messages back stating that these are landline numbers and cannot be texted; when I text the local numbers, I have texted a generic message along the lines of "I can't reach you on the phone.  Please call me as soon as you can" but I do not receive a call back.
We cannot speak directly with our employee right now (he is in Mexico to pick up his elderly grandmother),  nor can we access our employee's phone to check the log, call history, etc. because he has the phone with him.  Due to this, when we discovered the high usage, we immediately "suspended" the phone line so that no calls could be made or received.  Subsequent to suspending the line, we have talked to his family a couple of times -- one time he happened to call them on another line, so we talked to him "indirectly" through a family member on another line with him.  He was alarmed about the calls and insists he did not make them. 
He does have children but they are forbidden (by him) from using the phone, and he states that he always keeps the phone in a case on his hip, thus no one else has access to the phone.  To go even further, it seems that most all of the calls to these unusual numbers are made on weekdays, during school hours, so I feel sure the calls were not made by his kids.
Calls to Verizon:  When we first called Verizon, they suggested we suspend the phone until we could speak to our employee.  Subsequent to our indirect conversation with him mentioned above, we called them back and told them he stated that he did not make the calls nor send the texts, and that we believed the phone might have been compromised, cloned, hijacked or whatever.  First, the customer svc rep looked at our account and suggested that we put an unlimited text on the phone for the current unbilled usage (there were a lot of texts, and we have no text plan on the employee's phone), and then remove that plan once we get to the bottom of this matter. 
Due to our concern about fraudulent usage, the customer svc. rep called the fraud dept. while my husband was holding on the line.  She came back on the line and told my husband that the fraud dept. said that "it cannot be fraud because if it was, there would be thousands of dollars in international long distance to countries like Pakistan and India." (WTH?)  Also, she said that it couldn't be fraud "because texts were sent to and from the telephone number so we know it was your phone."  (another WTH?)
She then went on to say that it looks like texts were sent to international numbers (???) recently (these same 523 and 352 area code numbers I referred to above).  Number one, if these were international texts, it seems odd to me that these texts show up on our billed and unbilled activity as "domestic text" and there is no premium charge assessed to our account for international texts.  Number two, if these numbers were international numbers, I imagine that we would be charged for outgoing international calls, which we were not.  Further, I imagine that the numbers would be displayed on our bill in other than a ten digit format, but am not sure, as no one has ever made an international call or text on our phone.
Next steps:
Does anyone have advice for the next steps we should take and how we can get to someone in customer service who can actually help us with this problem, instead of what we experienced on our previous call?  Can we demand that Verizon launch an investigation through its fraud department on the activity on this phone, or is this at the discretion of VZW to launch an investigation?  I am unsure, since this was not given as an option by the customer service rep... 
If we can get Verizon to launch an investigation, is payment of the portion of the bill with the unusual and disputed usage (namely, that which is over and above the usual usage) waived pending the investigation results, or will we have to pay the entire bill to both avoid having the phones turned off, as well as any detrimental effects to our credit?  We've been hit hard by the economy, both personally (I am out of work right now) and business wise (my husband's business has been doing only about 25% of its usual business), and we don't have the extra $$ for the bill unless we take it out of our grocery budget. 
If anyone has any insight, suggestions or otherwise, I sure would appreciate it.  Sorry for the lengthy first post, but I thought it would be helpful to outline as much about the situation as I could in order that people could respond.  Thanks in advance!

Answer 1

kbinga,
I know this is a confusing and frustrating situation for you. I would be happy to review the account in detail to see what is happening with the usage and charges to ensure it does not continue to be a problem for you. Please send me a direct message for further support assistance.
Thank you!
AdamE_VZW
Follow us at @VZWSupport