Yesterday I purchased a $5.8K B/SWU* ticket to MNL for late July. I am looking forward to the 747s (DTW-NRT-MNL and return) but confused by some complications.

First, when they calculated my MQMs they kept saying 18K. I insisted it was more and finally they said 27K. Is this because the same flight number is used for DTW-NRT and NRT-MNL plus MNL-NRT then NRT-DTW?

Also, I could not get my favorite seat (73A) for DTW-NRT because although it is empty DTW-NRT the same seat was not available NRT-MNL. The seatmap simply shows DTW-MNL and MNL-DTW. I have heard of this complication but find it strange that DL would not accommodate me with such an expensive ticket. I really want 73A for DTW-NRT and am happy with 77A for NRT-MNL.

Advice is welcome as I search for solutions.

*(Yes, this is my final SWU ticket. I knew I was going to MNL but was unsure of the dates so I extended the SWU [past 2/27/15] by purchasing a refundable B fare to MNL.)