Iphone X64gb & Iphone 7 128 Gb - Got physical issue

I am inviting this email because the quandary which I am facing is earnestly revolting. I've bought a contrivance of INR *****/- which is not even * year old and I started facing issues from day *. I complained a lot for the same but I didn't get any resolution for my problem. Now the new problem which I face is even after using the cover full time the contrivance got scratched from all the sides. When I went to the service centre the executive told me that you can not supersede the body and additionally they told me that If you use the cover the body will get scratches if it's a silver colour contrivance. This is genuinely a profoundly lamentable experience. Using cover for full time but still scratches on the contrivance. I require this to be superseded.