Paytm — product differ from image as shown

I have ordered a dell laptop model 3578 on 26th of february but the product which i received on 28th feb was exactly not the same as shown in the image. So i requested a replace to get the desired product but again i received the same product with a new packaging, this time i requested for the return but they rejected the returning of the product and now they are not responding to my request rather saying that the required specs was not mentioned but the product that was shown to me in the image contains the required specs needed to me. Now i don't want that product which is not fully desirable to me so please ask the company to approve the return request and refund my amount as soon as possible.