Denied booking

Booked a car, have confirmation mail and screenshot of reservation, was not given car because it was said that its not available... I was offered a much smaller car for 10% discount....
It is obvious that Europcar customer service director is sleeping as I did call the call center to submit a request for help, they said they will fix it the next half an hour, which I found out to be the time that they close for the weekend, so only buying time for me to find a solution by my self, the branch is hopeless. Now, I am without my car for the weekend as all other companies are double the price of my booking!!