Hi there Simonsays
In light of the comprehensive post by serfty above, I am more inclined than ever to believe that this is now a fight you will not win. But of course no harm in trying I guess.
It seems to me that (notwithstanding what might have gone before) Emirates are keen to draw a line in the sand and not be pushed into refunding amounts of money that they feel is not only unjustified, but - in fairness to them - quite irrational. They will have drafted their responses to you on the back of considered advice from their specialist legal team (ie rather than some unqualified member of the customer services department)
Plus ..... based on information provided by serfty, Emirates now have the full force of clearly-defined legislation behind them.
In short I find it hard to imagine any grounds for a Judge to rule against them.