Well, of course it scratches when you heavily use your fingernail.
I can scratch most of my devices with my fingernails if I try to do it.... though the black case was even worse, you didn't even need fingernails to scratch it.
You got a black case and didn't like it, you now got a silver one and don't like it, I don't have anymore cases to offer, I'm sorry about that.
I already paid more shipping costs than to ship back and forth the unit that I make profit with one unit, so the best way would probably be you send it back and I'll refund the money completely, as I just can't afford to ship it back and forth another time.
I'm sorry, but if I can't seem to provide to you what you're expecting, this seems to be the only viable solution.