I am trying to use UA miles to book a *A upgrade award on SQ. I called 1K desk and UA says that only SQ fare classes of Y, B and S are valid to use UA miles for *A upgrades.

On SQ's website it says I can use E class as well for *A upgrades. If this is true, anyone have suggestions on how to get my UA upgrade pushed through on SQ being booked in E class?