Nikon India — not replacing part under warranty

I had given my nikon d5200 in pune service center because of blurry viewfinder. They told me that my product is in warranty and diopter will be replaced under that, yesterday i got a call from service center and they told me that they can not fix this under warranty as there is internal damage, i asked them how i can damage the internal part of the camera if it was not dropped earlier by me and diopter is only used 2-3 times till now after listening this there answer was they are agreeing all this but they can not fix this under warranty.

This type of unprofessional reply is not expected from nikon service center.

Please help me on this asap.

Service req:pne-005078