Punjab National Bank [PNB] — Refund not settled

Address:	New Delhi, Delhi, 100001
Website:	pnbindia.in

I purchased something worth 1028 rs from amazon.in on 10th feb 2017 and cancelled the order the same day.
They sent a mail that refund has been processed and it will take 3-5 business days to credit it in my account but my account hasnt been credited yet.

I raised the issue with both the company's customer service PNB is denying any kind of transaction regarding the refund where as amazon has given a reference no. 4867171670146130203082 and Authorization code:- 056410 and suggested me to file charge dispute as refund never processed.

I dont know how to do that.
Please help me.

Name- Mrityunjay Kumar
a/c no. [protected]