ExpressToll Charging for 4 axle when I am a 2 axle and I can never get on internet to look at bill Aurora Colorado

I could never get on thier web site. Everytime I would have to call them and they would have to fix something on thier end. So I ask for a bill to be sent to me and they said it would be a $2.00 charge every time even though I am having problem getting on line. So I just canceled them, they said that they would send me a check for $6.40. But the next time I got anything for them was a bill, because my son took my car on the toll. I said that was fine but I still could not go on line to see the bill. So he told me what it was and let me know that they for got to charge me 1 toll back in Aug and it is Oct. Then he informed me that they charged me as a 4 axle not a 2 axle. So now I wonder how many other times that I did not check the bill if they over charged me or they seen that I was cancleing them and so all of a sudden they found another charge. They also wanted to charge some late fees. I did not want to give them a card over the phone but I did, I hope they don't all of a sudden find some more bill. I'll probabley be getting another bill saying they found another mistake and charge me againe Surprise Surprise. Put the cashier back so we know that the tolls are correct. You don't evern know where the tolls start or stop