[Johnngnky]

We already process a replacement with it and its been reported has faulty. At this moment on our end we can't process any replacement with your device

This ^ Is contradictory. Have they, or haven't they processed a replacement? It cannot be both. Also, they really need to work on their grammar- It's very poorly written.

I believe Logitech is saying that the S/N he used has already been used for a replacement

That's what they meant.
@mothered
I agree, thanks for the advice, elevating the claim will help,I think, but what do you expect.
They probably won't accept the request since the serial is used before and they probably know it's a se attempt.