DHL Express India — did not receive refund of the import duty fees that was collected twice

I had ordered medicine (RENADYL) from US for my mother's kidney treatment.
DHL asked me to pay Rs.1408 via online portal, and i did the same (UPI Ref no.[protected]

Then DHL informed me that they have not yet received the amount and asked me to pay the same amount via cash and promised me that they would refund the amount that i paid online, once it reflects in their system.

I paid the same amount again via cash and got the parcel.

The online payment was successful too, and is showing in DHL systems (acknowledged by DHL via mail) from past one month, but they are yet to refund it and are not giving any proper information via mail. attached is the mail chain that has all the details along with payment receipts.