gave me damaged car

i rented a car from avis on 3-09-2015 to 3-10-2015 when i went to get the car they gave me the key wethout any inspection of the car so when i got to the car the side spiles had a skrechh and also on the rear bamper and the front bampaer the i went to the guy who was helping another client and i informent him of my consern thats when i was told to not worry about the skraches as they are minor .i toke the car till the 3/10-2015 i was working on the 3-10-2015 so ask my big brother to take the car to them and he did that when he was there they complainet about the skraches on the rear bamper and front bamper so he called me and i told him that they said when i toke its was minor i should not worry 2day(8-10-2015) i got an sms saying that i damaged the car rear bamper and front that i must pay R2900 so i called them and i was told manager is not there no1 can help me .this is worring to me couse they did check the car with me and when i told them about the skraches they said is minor i should not worry so y am i getting this sms please help