Punjab National Bank [PNB] — amount is not credited in my bank account

I had to receive a refund of ₹949 from myntra bud did not received when queried from myntra they told that they have refunded the amount and gave me arn number and asked me to contact my banks customer care and giving them arn to track my refund. But when i called, the customer care executive didn't knew about arn and simply asked me to contact myntra and disconnected. Now myntra is saying to contact bank and bank is saying to contact myntra.

I want my money and pnb should track my refund.

Arn no is :[protected]