I've been trying to book KUL-AKL in flex Y and returning in flex J but of course the emirates website only allows saver Y returning in flex J. When I phoned the emirates call centre the price they gave for the latter was far more than the price the website gave, and obviously the former was more expensive than that.

However, the person at the call centre suggested buying a flex Y return and then going into MMB and pay for the fare difference between flex Y and flex J, thus getting the itinerary I want whilst paying the cheaper website price.

Does anyone have any experience of doing this? It seems too good to be true!