The best way to settle a parking lot accident, if no one was injured and both sides are agreeable, is to sign a settlement agreement in exchange for the repairs. The key is to make sure the person cannot come back after you. This is why it is critical to make sure the settlement agreement is written such that no further actions are possible, known or unknown. That is, you don’t want the person to come back later and claim their bumper was worse than expected, or that they were injured. You need to make sure the agreement covers everything. No doubt, you could get a lawyer to write such a thing. Or maybe you can find a solid one online.