The most expensive subway ride in my life (so far)

I was in New York City last October, and I bought a 30-Days-Unlimited-Ride ticket. It costs about $70. Actually I didn't really need it since I wasn't in NYC all the time. I was staying in Princeton many days as well. Anyway, I was holding it in my hand when I entered the subway with my luggage through the service gate. A police officer stopped me and issued me a fine for entering the subway without paying the ride. I showed him the damn ticked but to no avail.
I couldn't go to a personal hearing, so I sent them a letter where I explaned what had happened, and wrote something like "if I don't hear from you, I consider this case setteled".
Today I got an reply--after 4 months. And besides the fine they've also issued me an additional penalty for not responding. I think I have to learn a lot about American bureaucracy. In Germany I would have been able to defend myself. I'm sure I wouldn't be in that situation if it had happened here. I'm really pissed ...