Harris County Toll Road Authority Need help... How do I dispute these ridiculous charges. Houston Texas

I have recieved mutiple letters from Linebarger Goggan Blair & Sampson LLP. They are trying to make me pay $17.75 for a Toll charge that was $1.75!! I bought a EZ tag to commute to and from work everyday and I pass two tolls going to work and two tolls coming home. When I set up my EZ tag I forgot 1 letter of my License plate.... You would think that they would not let you complete the application if the license plate did not have enough characters but they do and my EZ tag was mailed to me and I stuck it on my car and assumed everything was ok.

Two month went by and I went to work everyday assuming that it was being deducted from my account. On the third month I revieved a letter with 200 voilations for the last 2-1/2 months.

Long story short... It's been around 60 days since I recieved the letter from Linebarger Goggan Blair & Sampson LLP. The next step is a Administrative Hearing Officer (judge). Hopefully he will see that this is a misunderstanding and only charge me for the tolls that I owe. Should I contact a lawyer to represent me in this Hearing?