Original flight was HKG-SFO-EWR in V class.

I called the Premier Desk to see if I could return two days earlier.

The agent said there was no change fee for HKG flights (presumably, due to the civil unrest). However, there was a fare difference since the new flights were a higher fare class.

I asked which fare class the new flights were. She said 'V.'

I asked if she could see what my original fare class was. She said the original fare class was V.

"I don't understand. If my original fare class was V and the new fare class is V, why do I need to pay a higher fare?"

The agent got mad at that point, so I just bit my tongue and paid the $47.

My understanding was that you only needed to pay a fare difference when you're changing your ticket to a higher fare class. I called back to ask another agent and the second agent said it's possible to still have to pay a fare difference when you're changing a ticket and the new flight(s) are the same fare class. The agent said I was originally scheduled to leave on a Tuesday, and now I am leaving on a Sunday and "fares on the weekend will always be more expensive than fares on a weekday [even in the same fare class.]" I know there are multiple fares that are filed with the same fare class, but I don't know if that even factors into fare differences when you change your ticket. Maybe I'm confusing ticket changes with SDC, in which the fare class rule applies?

Does this sound right (that it's still possible to have to pay a fare difference when changing your ticket to the same fare class)?

It sounds right. The fare in a given bucket changes frequently.

Is this the return portion of a RT ticket? Changes made after the outbound portion has been flown tend to be treated differently.

Have you found your original and new fare codes and tried to read the fare rules? AFAIK it could even be the same fare code with a surcharge for Sunday travel, just like some fares permit a stopover for an additional fee.

The second agent was correct, and you are indeed confusing slightly with SDC, which technically should be the same but (a) you usually don't SDC to a different day; it's literally "same day" change, and (b) the way SDC is coded and usually handled, the standard rules check is ignored, probably because as originally envisioned you would not be doing an SDC in a way that could break your existing fare rules.

It's extremely common for international fares to be valid only for certain days of the week, usually with two schedules: W (weekend, higher because business travel usually isn't on a business day when int'l) and X (the other one). For EWR-HKG, template W is for travel Fri/Sat/Sun and template X is for travel Mon/Tue/Wed/Thu in each direction, and the templated fare difference is $50 half-round-trip. Usually, but not always, the same fare family has an X and W version for the standard difference.

UA often publishes multiple fares for a given inventory bucket, with different fare rules and pricing.

Also, if you haven't yet flown the outbound, the ticket typically reprices on a change, and may be subject to current rather than legacy fare rules.

There can be multiple fares that book into the same class, each with different requirements/restrictions, at slightly different prices.

Also even for a given fare, the price can change over time.

Booking class doesn't tell nearly the whole story on what the price is.

Yep. Not sure what the difference would be in this case (in the case of return portion of RT).

Should have done this but I didn't. I probably still could if I look in the 'Past Travel' section of my itineraries... right?

No if you did not record the original fare basis / fare code, it is tought to recovery

presently there are 12 different V fares for HKG-EWR
Same have different valid dates, some are RT only, some OW, ....

Could it also be a surcharge tied to the specific new day of travel?

I know US carriers often add an extra charge into fares departing certain peak days - around holidays, long weekends, etc. My understanding is the fare difference shouldn�t apply if one is booked into the same class, but if there is a �peak day surcharge� (for lack of a better term), that might?

You might see 10 variations of VXXXXXX at any time on any airline, to say nothing of the first ticket meeting conditions on the original V which now only meet conditions of new, more expensive V. $47 is not worth an argument unless the original fare was $3.

No, not correct for a standard flight change. The exception is SDC. And some waivers.

Surprised nobody has commented on this part. Right now there is no public waiver for HKG flights, so you should've been charged a change fee. If there was a waiver, then those rules would apply. Some require the same fare class/code to be available, some only require that it be the same cabin.

Sure somebody else can explain this better, but essentially the difference is if you haven't flown any of your trip, any change requires that the WHOLE trip be repriced. Whereas if you've flown the outbound, and you're only changing the return, then only that piece gets repriced (and if I recall, can keep the same rules, advance purchase requirements, etc. of the original purchase).

They either waive the change fee only, or both the change fee and difference in fare. Nothing special about same booking code.

On many fares, you can still use historical fares and measure advance purchase from the ticketing date as long as you don't change the first segment on the itinerary, even if you haven't flown any part of the itinerary.

More or less, any change (except for SDC) requires a reprice, it's just that you usually get more favorable conditions (use historical fares, measure advance purchase by original ticketing date, etc.) if you don't change the first segment. Even for the flown segments you could still end up in a different fare for both the outbound and the return, though, if your change the itinerary so that it no longer meets the original fare rules (e.g. you shorten the trip so it doesn't meet the minimum stay requirements).

OP should be aware that the weekend departure to/from Asia is about $50 more expensive than weekday departure if OP does a mock search. This discussion should end at the second post.