I personally heavily disagree with that damage being remotely related to your phone's issues and find it odd that it's being refused for a few scuffs, but as on your other post it was suggested this could be from a drop, and in turn causing internal damage, which then is a chargeable repair. The only problem is there's not much on the forums we, as customers, can say or do to change that decision.
You could reach out to Samsung support again and request another repair, or go the legal route such as consumer rights.