Letter required from Postal Service to state that an address is not valid.

Description

I am currently have a resolution case before PayPal. I was instructed to return the items to the seller, address was supplied by seller. I copied and pasted the address as supplied by seller.
I attempted to post the item and was advised by the Postal Service that delivery could not be achieved as there was only a street address, no suburb or area code. I would have thought this was obvious however, PayPal now say that I have to get a letter from the Postal Service stating that the address is incomplete! Really? nobody at PayPal could look at an address and realize that with no suburb or area code would mean it is incomplete. It’s for China!
It is hard not to be cynical and think this is PayPal introducing unnecessary process to discourage claims. A Google search revealed hundreds of complaints against the supplier, why aren’t PayPal introducing measures to ensure a code of conduct by sellers.