South Indian Bank [Sib] — refund not processed

I am a sincere account holder at your bank bearing account [protected]. On July 27, 2018, the refund from Amazon India was processed successfully and supposed to reflect my account 1st August 2018. I contacted the bank's customer care many times to understand the reasons for the delay in crediting.
Pending transactions details,
Rs.399, processed date: 7/26/2018, transaction reference number: 37740135.

There is absolutely no doubt that, this delay was happening on the bank side and like to know the reason for it. It is really sad to see the poor service from the customer care about this request. As your valid customer, I request to know the reason for pending my transaction and make the necessary steps to reduce my struggles.
I think my request is genuine and hoping to get a valid reply from the South Indian Bank.