Ecom Express — Flipkart Item

I ordered an item from Flipkart and had to change the address for faster delivery before the item was shipped. The delivery was scheduled earlier than usual, and the delivery person said he would call me in 5 minutes. He never called. I tried calling him, but he rejected each call. It has been four days since, and no delivery attempt has been made. Further, the item shows undelivered. I want the item to be delivered and I am unable to reach ecom.