Originally Posted by
chitownflyer
The change fee is supposed to be based on what the fee was at the time that you cancelled, so you should pay the old change fee of $100.
Clarification (IMHO) - the change fee is supposed to be based on what the fee was in the fare rules for your fare
at the time you purchased it. Not what it was at the time you canceled. I've reused canceled UA tickets for $100, after they changed the fee to $150, because the ticket being reused had a $100 change fee in its fare rules. That's what I agreed to at time of purchase of the original fare.
The new ticket issued using the value of the old ticket, will have the higher change fee if you change it again, because the higher change fee is in the new fare's rules.