HDFC Bank — am not received cashback

Address: 108 19 th main JC NAGAR MAIN road Kurubarahalli Bangalore 560086

Hi this is NAGENDRA R
Am purchased a I phone through Hdfc credit card 4 jan 2020 that time bank people are told to me you will receive cash back of 6000 within 120 days still am not getting any cash back it's already over 120 days there is no response from HDFC Bank Please check and update my account please reverse the payment ASAP