User Activity

I am so fedup with Australia Post. It appears that item has not been received by buyer so refunding is going to happen. Why am I held responsible for something that is completely out of my control. No one wants to pay for registering their item yet I...
I have had an enquiry about buying more than 1 of my items. How do I raise an invoice for bulk items. Shw wants 10 of the same item. My listing is for 1. Many thanks