[Resolved]  HDFC Bank — hdfc cashback not received on purchasing iphone 11

I purchased an iphone 11 with my hdfc debit card because it said there was a running offer which would give me a cash back on the purchase of iphone 11 and its already 120 days but i haven't received my cash back. The bank when called refused to solve the problem. I got my phone on 4th jan 2020 from a store called mobile planet in mumbai. Because of the covid situation i am unable to go to the bank too. The bank isn't accepting any calls and the shopkeeper says they aren't reponsible for the same as its between the bank and the customer