Issue with warranty/invoice

This is not a technical question, if i'm posting in the wrong section I request the moderators to move it to the correct place.

I'm from India. We have an online shop here, called "Snapdeal". Purchased a laptop from here, it's a Dell Vostro. When I check the Dell warranty page, I see the "Shipping Date" is different from the date on my invoice. Called up Dell support, they asked me to mail a scanned copy of the invoice, and they will make the appropriate corrections. I did, and the next day Dell called me back and informed my request has been rejected, as there's no "Service tag" or "Express service code" mentioned in the invoice. It's impossible for Dell to verify this invoice is for the laptop in question, and i need to contact the "place of purchase" for an updated invoice which includes the service tag of the laptop.

I've since called "Snapdeal" a number of times. They keep telling they have taken a complaint and will send an updated invoice in 24 hours, but I'm yet to receive this.
This is not really a Dell problem, it's a "Snapdeal" problem. Could someone please suggest what do I do now? If the laptop gets stolen, I won't even be able to complain to the police, as my invoice is pretty much meaningless without the serial number of the laptop mentioned on it :-(