I stumbled upon a site called Frank's compulsive guide to postal address. Like a typical resident of a pocket-sized country I checked if it is any good - if it mentions Slovenia. And it does! How cool is that, eh?
Of course it was too good to be true. It was more Slovakia than Slovenia. The link to Pošta Slovenija national post was that of Slovenská Pošta. Not again... Few lines lower the link was correct so I decided to write to Frank and inform him of his mistake.
In just a day, Frank answered, thanked for report, said it was a sloppy editing that caused the error and he fixed it on the spot. Way to go, Frank!
One small victory in an endless (pointless?) battle.