Myntra.com — Missing product from delivery

I have ordered two dresses from Myntra and paid in advance and it was initially due to delivery on 13th Oct but delayed and packet received on 17th Oct and delivery guy marked both products delivered, on opening packet one product was missing checking with delivery guy he said they scan bar code of packet they do not know about what’s inside packet. Raised a complaint on customer care where they said they will resolve it after investigation maximum by 20th and on calling on 20th they don’t have any update and again asking more days and my money is with them