Originally Posted by
Often1
Credit card dispute won't work and can hurt downstream. What US did is poor CS, but it's not wrong under the t&c. They are entitled to collect the fare difference and you could have cancelled at the airport and not flown. In a chargeback, you will lose. Put simply, poor CS doesn't translate into a legal right to a refund of the $108.
Yes, try to resolve it with US first, but they're still in the wrong and if they won't budge I'd do the chargeback. It's true he owes the difference in fare, but he paid the quoted difference in fare when he paid the change fee. It's not his fault US changed its mind about what the difference in fare is. The fact that the change in fare + change fee exceeded the cost of a new ticket is evidence that he didn't agree to the extra $108 up front.
It's simple -- they quoted a price for changing the ticket and he paid it. Requiring additional payment is breaking that contract. Their ability to play the "mistake" card is limited in that it's not an obvious off-by-10x error, and an actual human looked at it and approved it.