Flipkart - Mattress size not ok

On **th of April purchased an item from Flipkart that is a foam mattress of the sleepins company. The order ID of that mattress was OD******************. The size which was ordered by us was not as we are expecting. So it becomes problematic for us when the order was delivered to us. We made a replacement request after the replacement was done they sent me the same size item so again we made a replacement but they cancel our replacement request. We just need that item should be replaced by the desired item which we are looking for or we should get our item refund.