Myntra.com — nike sweatshirts/receive a defective product

I have ordered a nike sweatshirt from myntra. When i received them item it was very dirty and smelly. So i created a return request for the item. And register a complaint against the order in myntra on around 25 dec. They assure me to resolve my concern in 72 hours. Whenever i talk to myntra they have only one answer our team is working on your concer and your problem will be solve in 72 hours and its almost 20 days and i didn't get any update from myntra. I am very disappointed from myntra. Please help me in this matter. If my problem didn't resolved in 24 hours. I will file a case against myntra in consumer court.