You are spot on, eBay DO ignore most emails, those that do get replied to are just auto bot responses

Far better of to use the have us call you feature (and better yet, use that and ask to speak to a supervisor

I can only speak for myself, but advanced search /within set number of km is fine for my post code

(I don't generally go to 'advanced search' for that though, I usually just use the 'with x number of km) on the left side of the page

Overseas items will come up searching OZ only becuase the seller claims the item is located in Australia (which it may or may not be) but the seller is registered oveseas 

I doubt the the so-called tech department even know because *most* of the time when eBay CS say they will escalte something to the tech department it is just bull dust to get a caller off the line as quickly as possible