HDFC Bank — iphone 11 cashback not received

I have a complaint against my purchase on debit card. I purchased an iphone 11 on 2nd december and i was promised a cash back of inr 6000 after 120 days from the last day of december. It’s been 123 days and i still have not received the cash back.

This is not the kind of service that i expect from hdfc bank, the customer care is not supporting me in any ways, they are just registering complaints for against or loss of cards.

Kindly look into it and let me know the course of action as soon as possible.