Complaint Review: North Texas Tollway Authority

I purchased a 2016 Toyota Camry in April of this year in Longview, TX. In August, I received a ZipCash Toll Bill for $5.48. I called these people and they told me that they had my car, in June, in Dallas,TX on a tollway without paying the toll. I haven't had my car any where near Dallas. I believe that I received my permanent tags in june.

I don't know what has happened here, but the only thing that I can think of could be that the car dealer may have used the temporary tags to transport another Toyota to Dallas.  

I've called NTTA twice trying to correct this issue with no results. Today I received a 3rd bill for $40.48. Please help.