Verison wireless Ran up usage time which caused $240 fee by using my AOL phone acct. Jacksonville, Florida

Just got new Samsung Galsxy s5 phone through Verison.  

I think Verison has ran up my usage time through my AOL account.  It is the only app. that had the 8 megabyte usage fee.  $240. was added to my first bill..  I've spent a few hours on the phone with reps. and at the Verison store.  They are supposedly doing an investigation.  Its a lopsided situation whereas they can't show you what the $240 bought.  The only app. that used the time was the AOL acct. and I think Verison engineered it from their end to get revenue from a new unsuspecting customer.  I got no notices of high usage.