Amazon.in - Product not delivered no refund as well

I placed an order on Nov **th for Realme mobile phone from Bangalore at Amazon.in website. It was supposed to be delivered to my sister in Delhi on Nov **th. I got all the messages, except from any OTP at delivery time or no call received of a delivery agent. Same evening I checked in app- it says product is DELIVERED. I was taken aback and asked my sister. My mother and sister informed nobody came, no parcel received. I contacted customer care and followed up everyday till Nov **th and they kept on telling, wait ** HRs, it shows Delivered, wait more time. Ok, wait more time, we will do investigation... On Nov **th I happen to speak to Delivery agency in Delhi whom Amazon connected me to speak to, that guy told we delivered, but we dont know who delivered.wow!! I called at Delivery agent no. the msg which i received on Nov **th. That agent informed I didnt deliver any product at that area on that day. And when I am asking to that agency, that person stating being trembled- "Ummm amazon will inform you who delivered and what happened", and when I am asking him bring the person in front, he has no answer! AMAZON is playing games, i dont whats their internal policy but this time they deceived me after so many god history with them... I am so angry and I am ready to file a case against them if they dont appear back with either a replacement/refund and an APOLOGY. Now they are not even answering my calls and just disconnecting calls saying no refund, we have closed INVESTIGATION without giving any clarification...seriously!! cant believe its AMAZON....