Damaged when parking foreign car, doubts about the cost

Hello, I’m not quite sure if this is the right forum, but I didn’t find a more suitable category. I missed a standing car (Polo III (Type 6N)) last weekend while parking backwards. He was standing behind me on the left and I then put my left part of the rear bumper in two small abrasions into the bumper of the polo. I have only some very fine scratches, but they can be polished out (Alfa Romeo 147). So wait for the driver, who was a young woman with about 20 years of age. I gave her my contact details and she said that she would drive to the workshop and then report to her. At the beginning of this week the father then contacted the driver and said that he had a KVA over 800EUR, because apart from the two known paint damage would also be a dent in the car and also in the side part some paint damage. In addition he would insist on a rental car. In my opinion, however, I could not have touched the side part. He listed his complete rights to me during the telephone call and wanted to urge me to pay immediately. At my request to be able to look at the accident damage again, he did not enter and otherwise he did not take up his negotiating permission, he seems to know his rights very well and to take advantage of them for his financial advantage. The fact that he doesn’t give me the opportunity to look at the damage makes me sloppy, whether the other alleged damages can be from me at all. The only possibility would probably be an expert opinion, but that I would probably have to pay myself… Whether this pays off for the ill-predictable chances of success is unclear to me Do you have any tips for me or do you advise me to just pay and let it be good… I hope someone can help me if Yes, thank you very much.