Refund of Rs.36999/- for purchase HTC 10 smartphone

On 4th April'17 i ordered an HTC 10 from online portal snapdeal.com for Rs.36999/- & got it on 13 April but after a few days i found out that the portal had delivered a lower version of the phone with a degraded hardware configuration which costs atleast 7-8000/- less on other e-com portals instead of the one they had shown on their website. Now when i asked for a refund they refused by saying that the returnable period of 7 days had already lapsed. This way they not only sold me a lower version phone but also fleeced more money out of me. Even the rear side of box packing of HTC mentions it as lower version phone. I have maintained all the original bills along with the packing & accessories & screen shots of the product on their website for future reference. Also note that even today their portal continues display a higher version of this phone. Kindly advice whether i can sue them for this fraudulent sale.