From your post, I presume they even got there without losing yet another aircraft, so a good result all round.
You're not kidding. That's about £1320. If the upgrade cost for the other legs was the same, that's £2060 to get a price for the whole trip.
Finn air do business class from £1723, although I recognize you might not want to start from Heathrow & my dates might be completely different to yours.
[Excuse any minor errors, as I'm trying to do this with no calculator]