Punjab National Bank [PNB] — refund not processed by bank

Address:

271001

I purchasedtwo itmes ₹1969 from myntra on 26/05/2018 and done full payment by debit card but order was returned on 07/06/2018 and now myntra is saying that refund has been send to bank.
So contact customer service and file charge dispute they had given me a no.

Bank reference number is - 75105178159001167009791
Bank reference number is - 75105178159001167178745

But customer service is saying they can file nothing like charge dispute and can only check if money came to your account or not.
Same behaviour by branch also.
Don't know what to do