HDFC Bank — Unclarified Debit Card Transaction Charges

I had booked train tickets through the IRCTC portal using my debit card. At the time of payment, the applicable transaction/convenience charges were already included in the final payable amount and were duly paid.

However, approximately 2 days after each transaction, an additional debit entry reflecting as “DEBIT CARD PUR ADJ DT //__” was charged separately to my bank account.

This has occurred in 4 separate transactions, and additional amounts were deducted each time over and above the original payment amount.

I seek clarification on the following:
1. The nature and purpose of these charges.
2. The reason for deduction after completion of the transaction.
3. Whether these charges were levied by the bank, payment gateway, or IRCTC.
4. The detailed breakup of the charges deducted for each transaction.