They are not food or perishable items. They are electronics.
The delivery was stated for today and till 9PM for that matter as per Amazon so I was shocked at how fast the return process was carried out.
Anyway, some more info. I ordered a bunch of items. First one was the order which was cancelled.
And now, just a while ago Amazon came to deliver the items, just when I was about to call the delivery agent's number (given in the delivery info). This time he called out my name from outside and I went to check it out. It was an amazon delivery and he said he also came earlier to deliver a package (the first one which got cancelled). It was the same guy! I asked him what exactly happened and he said he called my number a number of times and I didn't pick up. I asked him to show me the number which he had supposedly had been calling and it was not mine! We called the number while he was there and none answered. I asked him how he got the number and he said it was provided by the "system" and showed me a message which said "Call <my name> on this number. Name was correct but phone number was not.
Anyway I talked with the cs who escalated the issue with their senior and I talked to her and told her everything. She said she has raised a complaint against the delivery agent/company and that Amazon will initiate action against them which I hope they will really do.
The order, sadly, had been processed for return so I was told that there was no way to get it cancelled and the actions cannot be reverted.