I rented a car from Avis in France. The contract said the cost would be $393.90 US, but Avis charged me $966. Can I recover the excess over $393.90?

I rented a car from Avis in France. The contract said the cost would be $393.90 US for a rental from 12 noon 1 April to 11am 12 April. I ended up turning in the car at 11:55am on 12 April. Avis charged my credit card $966. They reviewed the case and said the rate was no longer valid since the car was turned in ¿¿¿late¿¿¿. I have turned in cars later than expected many times over the past 30 years and have never seen charges remotely like this. The car was returned in excellent condition, not a scratch. The gas tank was full. There was nothing on the contract that indicated coming back after 11am would cause an exorbitant penalty like this. I have been a customer of Avis for decades and have rented dozens of cars, most likely over 100 from them.