NTTA North Texas Tollway Authority Late Fees50%+ being chrgd w/o notification $473.90 Dallas, Texas

My first actual contact with the toll service was 2+yrs of chrgs including 50%+ late fees in one billing. $473.90. When going through a toll without money exchanged it bothered me. I researched on line to find out how to get a permit. I tried to find it in the phone book, looked on line with no success. After I received twenty three (23) pages; bills in one envelope requiring payment  $473.90 within days I called to inquire where I could have discovered how to avoid such fraud. Are there signs that tell a newcomer where to go? Is there a mention at the License Agencies? What information is available? Can the NTTA rack up a 50%+ late fess without first notifying their victom and allowing them the right to pay normal fees? Without a doubt, NTTA ripped me off!