How to fictitiously charge damage? – Paint damage

I recently got a “nice” scratch in the back door of my golf…about 10cm long, quite short under the window. KVA from VW says about 500€. They build up a part of the door and check the new…the clerk said, after he asked me if there is an “opponent” that you can’t do that with smart repair…(type that he wanted to know whether it should be cheap or I don’t care and when I told him that there is an opponent…) My thinking is now, that the The opponent’s insurance company has now written to me that it agrees with the KVA and that I should send the invoice after completion of the work… How can I get a fictitious bill? Then any things other than VAT will fall away?