Amazon India — amazon - refund not received

Address:	560102
Website:	Amazon.in

I had placed an order for Sony Xperia and cover worth 12178 on Amazon and cancelled the request on same day even before the product was shipped. I received an email stating the refund was processed with a reference number on March 17th, however I haven’t received refund yet. I contacted my bank and charged dispute and they informed that the reference number provided is invalid. The amazon customer service is disconnecting calls. I am extremely disappointed, frustrated and depressed.
Order number #[protected]