Originally Posted by plkong
so just buy a Y or B class and call SQ for an upgrade with miles?
Originally Posted by fumitani
Yes
Why would you call SQ to upgrade with miles unless you were using KrisFlyer miles? If you were using KrisFlyer miles, you can upgrade any paid fare bucket apart from VQGNT - ie. you don't need to buy Y or B when you can upgrade a cheaper E or M class ticket.
Y/B is only for *A upgrades - in which case you should be calling your *A mileage program (eg. LH M&M or ANA Mileage Club) to upgrade using miles.