Did I get scammed?

This evening I had to park my bike in some random residential lane just opposite to Marine street. Some random parking police came running along with the ticket machine and I had to pay ₹30 for 1hr. The thing that bugs me is theres no parking fee printed on the receipt. Today they charge me ₹30, tomorrow they might ask for ₹40/₹50/₹60? Kya chal raha h?