Legal question: damage to rental cars

We had a rental car because of the swap with the wheeled towing lever. I brought the car back the day before yesterday, I went around the car with the lady from the car dealership, she looked at it outside and inside (short), said it looks good. Yesterday came the call, that they made a clean up, found a scratch, whether we got stuck somewhere. These are neither Dominic (son) nor I – I swear, If I did something instead, I’ll give it to Dominic as well. I’m sure you’d have heard/noticed what it looks like in the pictures. It might look like if you were driving through a narrow alley in an old town and stuck on such a boundary stone that looks out of the ground or something. But we weren’t on the road. We both treated the car like a raw egg. I said that we weren’t, asked Dominic about his work again. There were only garages, work (Dominic), parking garage Ansbach or parking places while shopping. There were no snow hills where stones could have been or similar when we were driving with the A4. When we took over the car, we were still surprised that there were pine needles in the footroom. Thought, a rental car was handed over cleanly. Mr. Leis said that the car was fully fueled, that the car was not stuck. he lady with the key then said, no he is only half full. We also had to fill up wiping water. This has become empty during the ride although we really needed very little windscreen wipers. I guess that has not been cleaned by the previous customer, therefore was not checked and we should have been now. The car was frozen when picking up, so we could not even see if everything is OK. But I thought: “Oh Quatsc h” doesn’t need to… He wants to make up his mind today, who had it before. I just want to know if they can complain about it one day later, if they said on the day of delivery, “he’s coming to the washing now”. Could someone else have gone with it in the meantime… That annoys me pretty much because our VW dealer with whom we are friends, said that would not pay insurance… How should I behave?