If you have already sent the package and the buyer is yet to receive it you need to get hold of the courier you used and ask them where the heck it is 

Can you please stop traders using the word Leather as a descriptor when something is made out of PU (Polyurethane) it is not a tanned animal hide it is a man made product I don't mind if they say leather look but just saying PU Leather is a false statement as PU is certanly not Leather  this seller is a good example  https://www.trademe.co.nz/a/marketplace/mobile-phones/accessories/cases-covers/oppo/listing/3580022497?bof=9gswXkLw where the title of the sale is Denim Leather it's not until you open the trade that you then find out it's not Leather at all it's PU