Amazon, New method of fraud or system glitch??

Ordered an item and placed a replacement request as there is no refund. The return was picked up by an Amazon pickup agent, and he said he dont have the replacement he just came to collect the item, and the replacement will be delivered later. The Amazon return page says that i will get the during the return pickup. This was not what happento me. Same day I could see the replacement order was out for delivery and he didn't come to deliver the item for next 4 days. I contacted Amazon customer care and informed them about this. They told me to wait for 13 days as the return is in transit. Same day Amazon delivery executive came to my door asking for the old item and he had the replacement. He didn't deliver it as i told him that the item had already been returned. After some time, i could see the delivery agent updated the replacement order status as delivered. Still no reply or resolution from Amazon end. Seems to be a new fraud activity by the delivery agents or a system issue?? No idea lets see how it goes !!