HDFC PG sends "NOT CAPTURED" as the response code whenever Authorization is refused by the card issuing bank. HDFC doesn't go beyond this (in the API) to explain the reason for the authorization failure. However, HDFC elaborates if you reach out to them through their support channel.
All support emails must be addressed to firstname.lastname@example.org. Subject should contain MID (its the eight digit number like 7000xxxx) which is used for uniquely identifying your account. Subject should look like:
[MID: 7000xxxx] Failure reason for TXN_ID
In the above replace the TXN_ID with the epg_txn_id that JusPay sends you. You can also find this in JusPay dashboard. This is the ID that HDFC can use to trace the transaction at their end. Your subject body should be like this:
Dear HDFC PG team,
Please explain why this transaction: TXN_ID was rejected by the PG.
HDFC PG usually takes few hours to respond to these queries.