northwest parkway no bill debt collection colorado

I received a letter from a lawyer trying to collect a debt for a toll bill i never received. I have always paid any toll bills that i get and am sure this bill was never received by me . So i contacted northwest parkway reguarding this bill and was VERY rudely told that im wrong there right end of story. So i contacted the lawyer which sent the 80 dollar collection bill and was again VERY rudely told that i must pay this bill to which i have never seen before.  Upon some investigation on the internet i see this company is receiving many complaints for this same issue and may now be being looked at by the better business bureau, although im sure this will amount to nothing.