After uninflicted accident, after billing with the insurance, total damage detected.

Hello Motor Talk members, on occasion of the situation. On 08.06.2016 I had an unindebted (right in front of left) damage with my BMW. On 13.06.2016 a report was prepared by the expert of the opposing insurance. Here a damage of 7000,- € gross was determined by the expert. And a replacement value of 11400,- € (BMW 535d, 2005, 150tkm, full hut) measured. I had fictitiously calculated and paid me the 6000,- € net. Since I wanted to have an M-package retrofitted and everything had to be repaired in a car body operation of my choice. Now, due to the prepared report (the M-package, 2 headlights, bonnet and many small parts) were bought and also already with the repair and painting of the parts started. Unfortunately now in hindsight a non-reparable frame damage (cracked frame tips) has been determined. There are now costs in the amount of 5053,62 € (incl. the workshop rec) Now the reviewer comes for inspection and evaluates the “current” total damage. I will no longer want to keep the car after the determined frame damage. But now I have all the parts as well as the workshop bill on the leg. But soon (residual exchange) no more car and lt. evaluator I get now only 11400,-€ – the paid 6000,-€ paid out and the car is gone. I can not sit on the damage now, since I (and the workers) now my questions to you: Who is now to blame for this problem? Do I have to pay the costs for the workshop and parts myself? What should I do with the parts without a car? How can I make it clear to the insurance company that I can’t get an equivalent vehicle for €11400? How do you see this?