Amazon.in - Successfully Rescheduled Order cancelled by Amazon in

I placed a order in Amazon.in on *nd oct ****
Which was not delivered to me till *th oct **** so i called and informed them to deliver the product on **th oct ****as I am going out of station, they successfully rescheduled and they told me that my delivery date is changed and will be delivered in **th oct, as i repeatedly told and requested them not to cancel my order they assured me that it will not be cancelled and successful delivered to me, but today on **oct **** i received a mail regarding the same that amazon.in had issued a refund on my order,so I called and asked to Customer service about about the same, they told me it was undeliverable and dont know the issue and refused to give me a replacement.
I requested them and told that that the problem is at their end, the courier partner has not seen changed dates and send the courier back to Amazon warehouse.
Now i feel helpless as they refused to give me replacement and issued refund without knowing the reason and enquiring the issue and refused to compensate the mistake occurred at their end.