Delayed refund for returned product from online Apple Store

Purchased the product from online Apple store but i have cancelled the same and returned. it has been more than 10 days and i am yet to get the refund.Despite calling the apple support number of times i am getting the same reply that we have not recieved the product back to warehouse.

Addiing more to insult while checking the status online for refund it is showing that refund amount calculated in Zero.

Please suggest what needs to be done

[Re-Titled by Moderator]

Original Title: Refund for the product