How to complain on the apple case damage

Dear Sir / Madam

I own a Iphone 11 Pro Max and recently bought an Original Leather Case from one of the authorized sellers in Dubai - UAE within 2 weeks of using the case the case colour it is totally changed and from brown is now some how black color and looks a very dirty and used case.

Pls advise how i can make a complain.

thanks

Hadi E.

[Personal Information Edited by Moderator]