How does Dell support his customer ??? Dell 7348

 I bought the Laptop Dell about 4 months ago, model : Inspiron 7348.today, i see a problem with my laptop : the powder coating at the left-lower conner was foamed and the color was darker (original color is silver).I think it is dirty.So i clean it and the paint cover was scratched.my laptop was urgIy. have contacted to Dell Support center in Vietnam.But i can not image that They said Dell can not make warranty.I ask him Why ??? He explained to me the issue is made by customer. how they can said that! It is so funny.i wonder whether the issue happen with other Laptop Dell ? and How did Dell support his customer ??? 

Now, I feel angry with Dell.and I also understand Why so many people choose Apple's laptop....