HDFC Bank — cash back not received

I have purchased iphone 11 from poorvika mobiles, kanthanchanvadi, chennai on 31/01/2020 using my hdfc bank credit card. I have been notified about an offer of 6000 inr cash back after 120 days of last day of transaction month. Now, the date have been crossed, but no cash back have been added into my account. Requesting relevant person to have a look into this and do the needful.