Originally Posted by
diburning
If anyone is still having this problem, this is what I do. I go search for the flight (as if I were looking to book it) and then view the seatmap there. Then, I DM my seat selection and PNR to them on Twitter (if you don't use Twitter, you can call it in as well)
Kinda a necropost, but I found this thread after googling for the same issue as OP. I can confirm that this method still works perfectly 4 years later. Had an ANA rerouted flight NRT-JFK end up as NRT-SFO-JFK with the second leg on B6. DMed Twitter and got it fixed in an hour (the reply was "We've assigned your seat"). Seat assignment shows up on B6 website.