Europcar ******* !!!!!!

I think I have been ****med by europcar like shown on Carte Blanche a while back. I rented a vehicle from them at king Shaka international airport for a period of three days. I was at a conference in the drakensberg and I did not have any accidents with the vehicle. Upon its return they noted a scratch on the left front bumper. I pointed out that I did not have any accident with the vehicle and that NO OnE checked it with me when I received it. Now they suddenly want me to take responsibility for a scratch that I did not cause. No one else drove the vehicle and I was at a conference. I am not a dishonest person and will own up if I did do something wrong, but this is just unacceptable. I will never rent from them again and will advise anybody to go with their competition AVIS from whom I always received fantastic service in the past!!!!