Title says all: I would like to book an itinerary available only from US point of sale (one way LHR-MEL in Y, which is not pricing out with UK point of sale).

Will it work if I call the US premier line?

Not sure it is a such a good deal in any case... SQ has pretty competitive prices through SIN, but their luggage allowance is minuscule, and mileage upgrades through KrisFlyer a joke. We are relocating, so a few extra suitcases at 200 USD each are an excellent way of shipping stuff we need immediately [plus upgrade lottery with SWUs since the one way LHR-LAX-MEL books in Q].