A little bit of advice sought.. thanks!

so today morning i was riding the bus on my last monthly bus pass that expired on july 1st. i know, i should have walked, but it was only 3 stops to gare cornavin to buy the ticket, and i had my passport and everything to buy my monthly 25 years or younger bus pass. the controllers got on, and gave me a ticket even though i told them i was on my way to gare cornavin, that i didn't have change but only a credit card (which i used to pay the fine on the spot... funny they take cards to let you pay a fine, but they don't have cards for the machines to buy tickets at bus stops), and that i have only recently come to geneva from the US and have only been here for one month. plus, i thought that someone at the ticket office had told me that they i was allowed to use the pass for an extra 4 days of the following month, like they do in san francisco.

basically, is there any way to fight the 80 franc fine? i am planning on going down to Bachet to the fine office to fight it. has anyone successfully done this? it was perfectly clear that i was on my way to buy a monthly pass (i had my passport etc), and in the US they would have probably let me go.

any advice greatly appreciated!