<While I've composed this, you have posted further, and I think the thing I would then say is that if an itinerary is changed (per the old way), and IF a flight credit is generated in the process, it will retain the old PNR. Its not the change of PNR which is the issue now, its that intermediate step of maybe creating a flight credit.> Viz:
I'm posting this mainly for others who are new-ish to this. What you say used to be the fairly simple go - I used it. But this time, there is a new T&C about
flight credits, which MAY make the old 'system' invalid. I don't wish to debate one way or another, but as usual, the addition of new T&Cs brings uncertainty which is what I wish to note.
Went through and checked the difference in T&C's between 2024 and 2025.
If anyone wants to read, I have highlighted the new terms in yellow that appear in 2025 but not in 2024.
Still trying to process what it all means..
with the relevant bit:
Flight credits issued on or after 12 March 2025 will not be eligible for this offer. ..... Any bookings made using flight credits outside of this window will not be eligible.
Now, dandandan posted, and included this link
which
implies that if you change the destination of a PNR created during the promo period,
after the promo period, a flight credit will be created prior to the new itinerary being created (with the SAME PNR) If this is the case, then it would violate the new T&C noted above, even though the PNR is the same.
Its new, so an unknown technicality but a change from previously worth considering. But as you say (and as my TA said) - going through a TA will probably overcome this uncertainty.