Originally Posted by
flyerdude88
The presence of V alone doesn't necessarily mean they are presently booking into that bucket (e.g., if you try and book JFK - LAX for this afternoon on the 825pm flight it's booking into U even though the lower fare buckets of H - L all are showing space). V might have had restrictions on it that because of the timing of your SDC call required her to put you into a different bucket to get the system to process the change and in doing so you ended up (mistakenly or not) on a YBM fare which auto-upped you to PN.
I believe your interpretation is incorrect. For a Same Day Change, it does not matter what fare is currently being sold. If the Fare bucket for which one's original flight is ticketed shows in Expert Mode for the new flight desired,then one can SDC to the new flight in that original flight fare bucket. Expert Mode also showed V9 after the SDC was made. Further, any Fare Rules or restrictions on the original flight ticket are ignored for Same Day Changes.