As my first segment was BA I just called them - got a good agent - she knew most of the rules - took down my schedule and its gone for pricing.

Question though - I have one sector SYD - PER on Qantas where Expertflyer shows lots of D class availability but the BA agent siad there was none (And this was for 2 flights both showing D). The BA agent was in the UK and I set Expertflyer PoS to be UK and all my other flights where I saw D being available were available. So what gives ? Why did the BA agent see D0 when I can see D6 etc and more important - how can I check to see if/when D class (from BA's perspective) might be available on this flight given that it is already showing available in Expertflyer