Amazon - Package not delivered

I had placed an order vide order number ORDER # ***-*******-******* dtd ** August ****. The status of the order was updated as delivered without actual delivery of product. I had immediately raised a complaint on amazon and was told to wait for * days. I called again after * days and my complaint was registered. Again I called and I was told that investigation has been initiated on my order to track where it is. After, several follow-ups I have been told that the order has been delivered to you as per Amazons delivery services/investigation team. It is really painful to see how Amazon is treating its customers. I asked for proof Amazon has that they delivered product to me and they have been silent on this. This is really very annoying. further, as per Amazon policy they take signature of the person at the time of delivery of the product however, they have not been sharing any proof and have closed the investigation without any valid proof.