I am not quite sure if this is the right SE site to post this. If not, I'd be grateful if you could direct me to a more suitable one.
A few weeks ago, I traveled to Bulgaria for a short vacation. I booked a few months in advance a 5-day car rental from fox rent-a-car, and got a confirmation email. Sadly, when I arrived at the airport the local company representative told me that they never heard of such a reservation (with the lame excuse that the reservation was confirmed by the global Fox rent-a-car, and not by the local Bulgarian branch) and that in addition that they don't have any cars to spare.
I was then forced to rent a car on the spot from a different company, which cost me more than double and caused a great nuisance and loss of time.
After I got back home, I tried contacting Fox rent-a-cart both (a) by email, (b) through their "online chat" (which is not online at all) and (c) by filling the form on their site. I got absolutely no response whatsoever.
What is the recommended course of action? Can I expect to be somehow compensated? If that matters, I am not a US citizen.