HDFC Bank — iphone 11 cash back hdfc not received

I have bought my iphone11 with hdfc bank debit card on 25/12/2019 in reliance digital, marathahalli, bangalore-560037. As mentioned by hdfc bank (To receive cashback of 6000 within 120 days from the transactional month end) i haven’t received my cashback till now, it is more than 120 days (Approx 240 days) i have been trying to reach out to bank and to the store but there is no response from them the store had told me that they will be providing an additional cashback of 2500 from reliance digital. I have been patient for so many months but nothing i have received. Please look into this matter urgently, hope this issue gets resolved and cashback will be credited as soon as possible.