Who watches the watchmen when it comes to Parking Tickets?

So I get a $160 parking ticket yesterday for parking in an Anti-Gridlock zone. The thing is – The sign clearly states that parking is ALLOWED until 4pm. I only had to drop something off at the UPS store real quick and it was 3:55. So I go in and out and I’m back in my car by 3:57 (no exaggeration). And I have a parking Ticket! I saw the parking lady and I was like, “what the heck?,” And of course she was the coldest, rudest, “I-hate-the-world” type person I’ve ever met.

The parking ticket is even time-stamped for 3:57!

I know the way the parking enforcement office works. It is Nazi-Germay down there.

My question is, who watches the watchmen? What Can I do about this?