Punjab National Bank [PNB] — Punjab National Bank [PNB] Refund from Amazon is not credited in PNB Account

I got refund initiated of amount Rs 17, 999 from Amazon on September 9, 2021 to my PNB account ([protected]) with refund reference #[protected] but the amount is not reflecting in my account as of now three days later. Calling Amazon they say I have to follow with PNB with the reference number, but PNB customer care says they can't help and I have to visit the Bank Branch where the account is. Visiting the bank branch did not help as the staff had no information on the procedure to be followed. Kindly help.