Well, I never got a reply to my on-lines enquiries - so I tried emailing various addresses such as [email protected] and got a response that way

Seems there's some sort of glitch that caused my online enquiries to not be received, while others' are received - this is being investigated

The response I received to my enquiry - about being charged a 4-continent fare for a 3-continent itinerary that has a SWP-Europe surface segment - is as follows:
I have responded as follows:

• The One World Explorer rules state “The fare to be charged is determined by the number of geographic continents in the itinerary including the continent of origin.”
• You are claiming that there is a “hidden” rule that adds an extra continent in the special circumstance of a surface segment between the South West Pacific and Europe
• So perhaps the hidden rule should be made public
• I also consider this hidden rule to be unreasonable because:
• More continents cost more – presumably because the expensive flights on an itinerary are the intercontinental flights, yet the itinerary I used as an example has only 2 intercontinental flights, and you say I should be charged as if it had 4 intercontinental flights
  
• The tool does not add an extra continent for other allowed intercontinental surface segments – for itineraries originating in the South West Pacific a single intercontinental surface segment is allowed between either TC1-TC2 or TC1-TC3
  I have priced up an itinerary originating in Australia and with a surface segment between South America and Africa
  Now the only way to fly between South America and Africa on a One World Explorer is via Europe
  (which is similar to the only way to fly from the South West Pacific to Europe is via either Asia or Africa)
  BUT the tool does NOT add an extra continent
  (the itinerary was South West Pacific --> North America --> South America --> Africa --> South West Pacific; thus 4 continents)