Amazon India — delivery of item not done

1. I had ordered Sony Extra Bass SRR -XB10, portable splash proof wireless speaker with Bluetooth and NFC on 17th Feb 2019 for which I made an advance payment of rupees 3299. The order number is[protected] .
2. I was informed by the Amazon app that the item has been delivered on 27th Feb 2019. However i had not received the item . Neither the delivery boy rang me up on my registered mobile number, nor i received any prior notification about the arrival of my order ( which always happens for any online purchase).
3. I had repeatedly called up customer care number of Amazon to register a complaint on non receipt of the item. Finally i was told that Amazon had investigated the matter and they come to the conclusion that it was delivered at my address
4. So i have finally approached you for help