HP India — Defective laptop

Address:

Meerut, Uttar Pradesh, 250001

I purchased a laptop from amazon india when i opened my product, in keyboard one of a arrow key (Down arrow) is damaged it got remove when you press that key because it was not damaged, i found that key in my laptop box because it is not placing on its original place
I yesterday my laptop yesterday - 13/08/2016
I only want that they replace only that key that is damaged but they are saying that they will not, please help me out as it was delivered to me yesterday
My invoice date - 11/08/2016
Invoice number - hr-del3-[protected]-231
I only want service from hp and that is only one key they have to replace please help me.
I will be thankful to you