Europcar- damaged car deliverd- and I need to pay!

I rented a car with Europcar almost a year ago. The day they delivered the car to my office the driver said it was very hot outside and I should quickly sign the documents at my table. I walked out side with him, he showed me the bodywork in a great hurry. Said that there is no external damage to the car and handed me the keys. When he left I got in the car and saw a big burn mark in the front passenger seat. I immediately phoned the branch, told them I did not check the inside of the car with the driver. They said thank you and that they will make a note of this. Months later a receive a call that I will be handed over for the amount of R3300.00 for the damage that was done to the rental car! They day I handed back the car I wrote on the comment section on the document what happened and that I will not take responsibility for the front seat. Now they also tell me that there is damage to the steelwork under the car? No woman will look under a car? I hardly had an opportunity to inspect the out side of the car. Even if I did look under the car on my hands and knees, what would I know about the framework? I Drove it for 3 days from work to home on a normal tar road!!!! (and speed)