Urgent Question about Expiration after Accident

Hello, I hope that I am right here in the forum. My parking car was striped by another car. The person called the police and passed on his data to them, they then informed me about the accident. The opposing insurance did not inform me of any damage number. She would like to contact the causer first. However, I should already have a cost estimate made and report to them. However, my workshop advised me The report would have to pay the insurance. Now I read in the forum of “debt question clarified”. Is the debt question solved automatically, if the victim informs the police or I would have to have the debt certificate given to me by the insurance company, BEFORE I have the report prepared, in order not to have to remain at the expense, if there is a rejection by opposing reinforcements ? The opposing insurance company said that it would be a new customer, where the data has not yet been collected. However, a cover commitment had already been given to the causer of the accident. I don’t want to do anything wrong, so I would be happy about your answers and experiences. It is about a VW Multivan Startline, built in 2009. The workshop estimates the costs roughly at about 6,000 euros. One last question: The impairment is certainly calculated by the Warkstatt. W ie is it with the loss of use compensation, if no rental car is taken, will this be paid automatically due to the report or only if the car actually stays in the workshop? Thank you