OP here. I don't mind sharing what happened. And knowing the details may help folks understand why we didn't address it with the manager before we left.
Yes, our stay was at POR. We actually liked the resort and were initially very pleased with it - room location was good, room and grounds were beautiful. But we ran into some bad weather - we were there last week for Andrea - so we decided to extend our stay so we could get in some more park time. We've done this once before at CBR and it was easy and convenient. Unfortunately it didn't work out that way this time.
I called Disney Reservations on Friday and explained that we were scheduled to check out on Saturday but would like to extend our stay and check out on Sunday. The CM checked and our room category was available and he said that we could book it and pay over the phone and then just go to the concierge desk at the resort to be issued new room keys. This is exactly how it was handled at CBR so we figured all was good. When we got to the concierge desk however, the CM called and checked to see if we could keep the same room and she was told no, that we would have to vacate the room. Their reason was that the room was part of a block of rooms that had been booked by a large group and they all had to be near each other. We let it go even tho repacking everything and loading it all back in the car was a major inconvenience. We also had to go back to the front desk on Saturday and go back thru the check-in line again. Also a big inconvenience. We didn't really get upset tho until we saw where our new room was located - right down the hall from our original room. We couldn't help but wonder why in the world the guests checking in on Saturday couldn't have been given that room so that we could have stayed in our original location. They would still have been close to the rest of their party.
We are not unreasonable - we would have understand if our original room had been handicapped accessible and the new guests needed that feature. Or if a larger family had booked two rooms and needed a connecting door between the rooms. But our first room didn't have either of those features. We would have also understood if the group checking in was a big school or dance group and chaperones needed to be close to the kids. (We're all for that.

) But we happened to see the new occupants (our original room was directly between our new room and the ice machine) and there was an elderly couple in our original room and no one at all in the rooms right around them.

(We weren't spying, I promise.

We just happened to see them as we walked by going to get ice.)
We were not going to make a big issue out of it but it turned out that moving to another room totally negated the advantage of having the extra day there. We had hoped to spend Friday evening enjoying the resort - playing in the pool and maybe taking the carriage ride around the grounds. Instead we were up until about 2AM figuring out how to repack everything so that we wouldn't have to drag every single piece of luggage back out again when we got into our new room. Then we had to get up early Saturday morning to load everything back into the car before we headed to the Polynesian for our breakfast at O'hana. By the time we finished our breakfast, got back over to POR, went back thru check-in, got our new room, and unloaded the stuff we needed for our last night and got it into the room it was after 3:00 that afternoon. And we were all exhausted because we had only gotten about 4 hours of sleep. We were just too pooped to go enjoy the parks - both kids crashed after we got into the new room and slept for several hours.
I have never filed a complaint with Disney before but I just cannot think of a really compelling reason why they couldn't have left us in our original room. So I hope to get some sort of explanation on that. And I have to admit, if they don't have a really compelling reason, I would very much appreciate a refund for that last night's stay because that ended up being a total waste of our money. I don't have high hopes for that. But I won't get an explanation or a refund if I don't ask. As for why we didn't address it while we were still there...well, by the time we knew where our new room would be we had already taken the time to repack and load everything back in the car. Our initial reaction was "oh well, the damage is already done." Asking for a refund did occur to us but it has taken awhile to convince ourselves to do it. That's just not something we would normally do.