HappyEasyGo — Refund not received even after 4 months

I had booked a ticket from HappyEasyGo with the "Free Cancellation" option by paying extra 500/- as per the terms. I had cancelled the ticket on 6th Sep 2021 and the website is supposed to refund me the entire booking amount after deducting the convenience fees. I have contacted HappyEasyGo multiple times inquiring about the refund status and each time I get the same reply that their team needs more time to process the refund. The airline informed me that they had processed the refund from their end on 6th Sep 2021 itself, the day I had cancelled the tickets. But HappyEasyGo Customer Support team kept telling me that the airlines take 45-90 days or 90-120 days to process refunds. I have waited more than 120 days now and the refund is still not received. And their reply is still the same. This is utter fraud on part of the website.

These are the details of the ticket:

Trip ID :[protected]
CCU→DEL
PNR: 5BRC8Z
Ticket No. :[protected]