We don’t think there is any official policy around this situation, but if you prefer a refund you should press for one. No guarantees but you certainly have a decent chance at it. A frontline agent is probably not authorized to do this so you may want to just ask for a supervisor right off the bat, or if the first agent you speak with says no.

Note that an even $500 sounds like a token (albeit substantial) gesture as the fare difference was almost certainly not $500 even. You could press them to prove to you what the actual fare difference was between a regular Blue fare and a Mosaic fare on the day you purchased the ticket. They may not even be able to calculate this so it’s a bit of a gray area.

Lastly, if the above is not getting anywhere, you could politely but firmly point out that if you file a credit card dispute with your bank, there is a very good chance they will side with you and then you will likely be dictating the amount of the refund because you can dispute any part of the original ticket price you paid. This may be enough of an argument to get things moving in your direction, and it’s certainly an option to pursue, although we’d recommend giving JetBlue the chance to make things right first before going down this road.