HDFC Bank — cash back not received

I purchased iphone xr in the month of december 2019, 5th dec 2020.
There is a cahs back of 5000rs which is supposed to be credited back to my account after 120 days of purchase.

I have not received the cashback and i have also raised this issue with the ban and no one sees to respond to this query.

I have even attempted to call them and write to them and i have no soultion to this yet.