Riverside Express review: Unauthorized charge

I live in Arizona. All of my vehicles are registered in Arizona. I received a letter claiming that I had a "Toll Evasion Violation" for traveling on the "15 Express Lanes operated by the Riverside County Transportation Commission". They listed a Vehicle Plate number we do not have and never had. The date they listed was a date were were not in California. They did not bother to include a make and model of the vehicle that they captured in their system. I called and spoke to a female in customer service who spoke to her supervisor and she was able to get rid of the charges claiming that the vehicle had a Washington State Plate with that vehicle number and that was the confusion. The problem is, I DON'T HAVE a vehicle with that plate number! Yet, for some reason, they connected it to me.