I parked at the green parking by Harbour and York near Habourfront boats. I bought a parking ticket that was valid from my time of stay until 7am. I went back in my car from work at 9pm and saw a courtesy parking ticket slapped between my wiper and my windshield. I read through it and it said that the ticket wasn't visible. I looked through my dashboard only to find that the ticket i purchased was upside down. Now it gave me the option to pay via online using a credit card or by person at the stated office.

My question is, is there anyway to negate the $10 fine by showing them my valid ticket?

The only way to dispute a Green P lot Courtesy Charge is to call the Toronto Parking Authority at (416) 393-7275 and ask them if they would be willing to cancel the charge if you show them your parking receipt. I don't know whether they will do it or not. However if you don't pay it I don't think there is much they can do to you. It is not a parking ticket issued under the Provincial Offences Act so it will not affect your ability to renew your licence plate sticker. The only thing that will happen is that if you get caught parking illegally (ie with an expired receipt or in a no parking zone) in one of their lots again you will be issued a real ticket instead of a Courtesy Charge.