Dell India — Warranty period

Address:

Rajkot, Gujarat, 360002

I have purchased dell venue 7 service tag no 7py3222 on 28/07/2015. On 27/07/2016 my sim card slot stopped working. I went to dell authorized service centre and to my surprise they said your warranty has expired in dec 2015 itself as warranty period starts from manufacturing date. It should have been updated by the dealer.
Whose responsibility is to update this. And who will pay for my losses. Even i talked to customer care and provide thm the option to mail the scan copy of the invoice but they refused. This kind of attitude is not expected from the company like dell.