Xiaomi India — used product selling as a new seal product

Address:

Gwalior, Madhya Pradesh, 474005

I have purchased mi y2 on 18th of november from mi home n block cannaught place delhi, they provide me seal pack box and open infront of me, after a week some issue raise in the device related to receiver when today i visited to service center here in gwalior jayendraganj infront of virasat hotel mi person of service center mr vipin saying this phone is already opened somewhere we cannot repair it under warrenty. He also shown me some points of doubt... I want to ask mi home store delhi if it is so why you people are selling the product.

I want some solution of my product purchased from them
I want a compete replacement.