Originally Posted by
maradori
Just because there are S-class fare basis showing in EF, it doesn't necessarily mean that there is availability in the S bucket. Use EF to check the seat counts for that flight ... most likely it'll say S0
I expect this is exactly the reason why the fare cannot be booked on that day.
Code shared flights will have each airline marketing and selling their share of the seats separately. That's why it will price out differently. I fly YQR-DEN-XXX every once in a while on a UA operated flight that AC codeshares, and more often than not the AC fare is higher than what UA will sell me the seat for.