Amazon India — Mobile Phone Missing - not delivered

I have ordered Google Pixel 6 for my brother on Amazon and got the delivery on 16th September 2022(Expected was 15th but I didn’t receive any call - they marked it as not reachable). After opening the package, I realized that the phone was missing and I immediately called the delivery partner. he insisted me to raise this concern with Amazon as his work is only to deliver. I raised the issue in Amazon app and was promised that it would be resolved within 5 days that is 24 September 2022.
When I called them on 24th they said the investigation team is working and they will resolve it by arranging for a return on 25th September 2022. I called them on 26th as there was no update from them, now they are telling that investigation team has closed the issue. Since I asked them to escalate the issue, they are asking me to write to [protected]@amazon.in