OUCH parking ticket but....

Send them a COPY of the ticket. Keep the original.

Who gave you the ticket BTW, where were you, and how much is it for?

Oh - and don't mention it was upside down. Just suggest they must not have seen it because here it is and it proves you had paid, therefore it must be a mistake on their behalf.

They take a picture of your front window, and if the ticket is not visible, you must pay the fine... You can try and argue, but I doubt you'll get it cancelled. I've read jurisprudence on this type of cases.

I was given a fine for not displaying a ticket on Place Meiser although I had bought one, I put it as usual in the drivers side of the window...but as the street was one way parked on the left side (so ticket was facing pavement) even when I produced it I was ignored, finally after several exchanges and threatening to go to the police the commune relented - but by then it had gone to a credit agency who got nasty even when i showed the letter from Commune rescinding it... As so often in this country, i finished up paying, running around trying to catch my own tail and 115 euro out of pocket even though I had done everything right. It was in Schaarbeek by the way next time you park there