I understand correctly that though you've managed to get a refund in the past through the NPCI, thus, it works, you don't have a prior experience of refund with Stake or any gambling site?
OP, Thamizan, do you mind to try to escalate the matter and get a refund through NPCI platform?
Yes, I got refund using this method but it's not from any merchant, but a person still it is same for the Merchants too.
The first 48 hours is the critical period and if the time frame is beyond 4 or 5 days then I doubt this method will work, we can try the bank customer support, but it's unlikely to help.
The stake support team replied that they're not recieving the cash after 23 days later only, the UPI dispute time was expired