Apple India — iphone 7 camera

I've purchased iphone 7 last november and the camera wasn't working properly with worst quality pictures and love in between the pictures clicked. I went to the apple store and your executive said he will fix it but it wasn't and the next time immediately i gave for service but it wasn't fixed. We asked them to replace but they don't. Look to it. We can't keep roaming for its repair and get nothing in return