The right to return a certificate

Good afternoon, I have a Leon 1.6 TDI, EZ: 6/14 mileage: 122,000 km In July the remaining rate of 5350€ is due. In the certificated return right the fixed buyback price stands at 5350 € at max. 151,305 km. Each kilometer less gives 4.05 cents plus the buyback amount. So, now the good unfortunately in the paint of the entrance areas has 3 scratches, which are not large (about 3cm long) but for a layman like me a little deeper than just superficial. Unfortunately, since July 19 we have been sitting on a Seat Ibiza SC 1.4 Style4you EZ: 7/14 with 47,000km, which can not be sold privately (that had/has not had familial so nice reasons) Why is it a mystery to me, by the way, because it is perfectly maintained, fully driving without defects with new TÜV, HU etc… Well, the fact is that no one had any serious interest so far and therefore I will take the right of return for the Leon and drive the Ibiza. Now my question, I should the scratch he has my trust made directly at the ywerkstatt or first introduce the car to the Seat car dealership as stipulated in the contract and let me know what I actually get for it? Sorry for the lot of blablabla. Is unfortunately a bit complicated and I don’t want to give my Leon any value or put it on it.