When I called, the agent could only see the higher fare. She checked with 'Operations' and they said a manager had looked at the issue and checked with the intranet and this route was a non-HBO route.
I said I could see the HBO fare online and that I'd booked HBO fares on this route before. The agent offered to book me the higher fare plus the £15 telephone charge.
I went for a walk to the bottom of the garden. I thought about making a cup of tea - but I didn't.
Palmer