I try to book an award flight in business class from Denpasar (DPS) to Jakarta (CGK) via Singapore (SIN) on Singapore Airlines. The first leg, DPS-SIN, doesn't cause any problems, but apparently it is impossible to book the second leg, SIN-CGK. The ANA website shows there should be availability in Y-class. The people at BMI too can see there is availability, but when they try to make the booking it appears the seats on that flight are blocked by Singapore Airlines. I have called BMI several times already over the past few weeks and tried changing the dates of my flight, but the situation remains the same.

Has anyone else encountered a similar problem? What are my chances for the seats on the SIN-CGK flight to still open up? And is this issue BMI specific or will it be the same of I try to use Miles and More or Mileage Plus? (I haven't tried either of those yet, because I would like to get rid of my BMI miles.)

(Note to anyone trying to book flights within Indonesia: The Indonesians appear to be heavily protective of their own airspace and favor their own lousy carriers. All of my searches, whether on ITA or Kayak, come up with Garuda Airlines as the only option. Good times.)