Booked next week on IAD-SFO. At booking this flight was operated by a 788. I selected and paid for an E+ seat in the PP section (although not marketed as such) for $189. Aircraft has been downgraded to a 764. I was re-accommodated in a different E+ seat, but the purchase price was really only worth it to me to be in a PP seat (yes, I understand it wasn't guaranteed because it wasn't marketed, and I didn't pay for, a PP seat on this route). I understand a refund just because of an aircraft swap is not going to happen. However, because the aircraft swap was accompanied by a schedule change I can change the flight for free. If I change to another flight and select an E- seat would I be refunded for the original E+ purchase? If I change to another flight and want to select another, cheaper E+ seat would I get any differential refunded?