Snapdeal.com - Defective item delivered

I ordered treadmill of **k and they delivered the defective item . The treadmill is not working.then I raised replacement for the product thinking it was mistake. While raising the request the status says the pick-up will be done next * days and then the replacement item will be sent ...after a week I am getting a mail which says we can not initiate replacement and send us the item on the required address. I have ordered **k item from their site and they are not even arranging a pickup rather asking the customer to ship the item of more than ** kg back to them . I have raise concern .no reply on that