Hello Subhadip (ray_subhadip),
Thank you for posting your concerns on the community boards and sharing your concerns with us.
As Faheem (game_mastr) rightly mentioned, you should contact your seller through this link and express your concerns. Alternatively, you can contact him on his contact number in case you had saved the same in case the seller contacted you.
I see that the seller had mentioned a 3Months warranty for this handset which is still applicable and hence you should not delay in contacting him and I'm sure that the seller would co-operate with you. He is a reputed PowerSeller on eBay with a good past record and would definitely help you in this regard.
Keep Posting!!
Regards,
Indraneel