Have paint damage repaired before leasing return?

Hello dear car friends, in a few months I will hand over my BMW 520D, but I will not take a new BMW with me, because I change to Mercedes. Now I want to carry out the return as cheaply as possible. It is a private leasing with mileage billing, as usual with BMW. In 36 months 60tkm were driven, as agreed in the leasing contract. So already no costs for more kilometers. But now I have a damage on the rear bumper, which is safe with the Rüc The BMW Leasing Agreement states that you have to have all the damage repaired at BMW. I already talked to my salesman. He said that this is not seen so closely. Nevertheless, he advised me not to do anything and to leave the car damaged. That’s the best thing. A friend of his paintmaker said that he could paint the bumper and a paint sealer could not recognize it. I have an offer of 400 € for the painting of the whole bumper. This paintr also said that BMW would probably charge a new bumper for the return (150€) Can that be? What are your experiences here? How would you proceed? Thank you for your answers.