HDFC Bank — Cash Back Not Received beyond 90 Days

I have purchase a electric item from Samsung Dealer at Ghaziabad on Dated 17/10/2021 and there was 15% cashback if you pay through hdfc bank credit card but the cashback amount has not been credited in my account. It’s been a long time and no one is paying attention to my complaint neither hdfc nor samsung dealer. The cashback has not been credited in the account despite being more than 90 days