I have a round trip to New York in Business Class coming up in August. One leg of the trip is with BA via LHR. I booked the trip on the aer Lingus app. As the booking had a BA element I had to ring the call centre to change it. They quoted me over 3K per passenger for a one day change! To book a brand new one way flight it would be about 2k according to the website. I can’t figure out how they quoted me a price which is supposed to be fare difference but is way more than booking a brand new flight. I asked the agent but they just told me it’s what the system told them. I was looking to change the IE direct flight so none of this makes sense to me!