Repaired pre-damage —> New accident

Moin! I would like to share my current situation with you and hear your experience if someone had similar. My vehicle had a repaired damage to the passenger door, which according to the dealer was fixed for approx. 250€. In addition, a rear damage i.H.v. approx. 4000€ was also fixed without invoice. (In retrospect I am smarter and would only buy accident-free vehicles, whereby the purchase price was very good). To the problem: I am in parking condition (have on the other side of the car). n side parked) a van drove into the side and took the whole side with him, including damage on the axle. On the rear bumper is a approximately three hands wide scratch damage. The passenger door is also damaged. My expert doubts that the insurance regulates the damage so, because for the pre-damage there are no invoices. To the question, if one could not calculate the pre-damage, he could not answer me exactly. damage is very likely due to the axle. I would like to avoid long processes that allow the pre-damage to be calculated out. Is that possible and how would one calculate if the vehicle had a value of 20k (accident-free) 20k – pre-damage 1 (-250€) – pre-damage 2 (-4000€) replacement value at the time of damage 13500€? Thank you