HDFC Bank — regarding cash back on iphone 11

My main concern is I bought iPhone 11, on credit card with sceme of 6000 cash back, I dint received any cash back which was said to me in 120 days, you will get an EMI of 5650 but still you guys deducted 11650, I am really very disappointed by your service, I use to think you are the one with standards very first Time I used your service