Happy New Year!

For most of my international trips, I usually book my flight on Mon-Thu for lower fare. However, sometimes, I want to change the date of travel (usually the return flight) in accordant to my schedule change. That day can easily fall into Fri, Sat or Sun which a higher fare will apply.

My travel agent can help me change the date of travel and always tells me that, from her experience, 1k/1p will very unlikely be asked to pay for the difference when checking in. However, I still concern about the risk since it can be a few hundred dollars depending on the class of service. Early this month when I returned from TPE to SFO, I will told that the fare difference would be $500 for C.

Any comment?