Join Date: May 2004
Location: SIN (LEJ once a year)
Programs: SQ, LH, BA, IHG Diamond AMB, HH Gold, SLH Indulged, Accor Gold, Hyatt Discoverist
Posts: 8,826
It is a one-way flight redemption right? Did you try to insert a stopover (>24hrs)? If yes to both, that wouldn't work, not be permitted. If your stop in IST is less than 24hrs it should be okay.
Sometimes you have to HUACA and get a different agent. Best to call the number in Singapore and not some US local number or so. This should be permitted as one ticket. Ask for a supervisor and an explanation if all fails. Aside from married segment issues this should be bookable.