Consumer Redressal

I have purchased a HP mini laptop from HP world, Shriram Computer (seller) at Dadar West on 06.12.2011. When I bought laptop it was represented by the seller that, my laptaop has 3 years warranty, however, now I have been told by the customer care of HP that it has only 1 year warranty, which has been expired on 05.12.2012. I raised this issue to the seller, but he is declining about the fact of 3 years warranty. The Tax Invoice given by the seller does not show any warranty period for laptop. Kindly, help me to resolve this issue and get my remaining warranty for laptop assured / promised by the seller.