A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
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.