wrote:

So, basically Canada says I didn't file a flight plan and I don't have
any way of proving that I did. Anybody have any ideas on how to
dispute this or had a similar experience? (AOPA Legal was no help.
Their only suggestion was the FOIA request.)

I would tackle as a customer/vendor relationship.

Write to this agency requesting that they wave the penalty, which will
encourage you to again fly into Canada and spend your money in their
country for more enjoyable services such as hotels, restaurants, and
entertainment. Send a copy to the Canadian aircraft owners & pilots
organization and the Canadian tourist board/agency.

Inform this group that you did file a VFR flight plan and that you
performed extensive research of the requirements of flying into Canadian
airspace before taking the flight. Let them know that flying into Canada
is a method of transportation that allows you to take more vacations into
their country than you would otherwise.

Conclude with the fact that if they continue to insist on penalizing you,
you will never again take another vacation into Canada and the $250 you
send them will be the last dollar you spend in their country ever.
Furthermore, you will spread the word via the Internet that Canada is not a
GA-friendly country and you will encourage every pilot you know to avoid
Canadian airspace and the businesses that thrive from this mode of
transportation.

Living in New York state, I used to drive over the border to buy Canadian
beer when I was in college (back before the days of good micro-breweries
here in the US). One time while eating at a small Canadian city
restaurant, our parking meter ran out before we could refill it.

Upon returning to the car, we spotted what looked to be a parking ticket
under the wiper. This is roughly what the ticket read (no lie): "This
paper is to inform you that your meter has run out. However, because you
are from a different country, we are not penalizing you. Instead, we are
thanking you for your business in our country."

I thought that was pretty classy.

--
Peter