When I calced EK to Genesis, I took the EK prices as including GST, didn't notice the Plus GST tick box. I did notice it, but after allowing for Genesis as incl GST and deduct discount to get a true compare I failed to notice it later.
So my 24.5c net for Genesis now compares to 23c not 20c with EK
Oh well. Still a small saving, after I recoup $12 for daily charges, and off course the free hour. But 15% is a big dip!