Yes I did get that, but nowhere does it clearly state what I have done (i.e. upgrade) or how much the change cost.

I suppose someone could compare this with the original receipt and see the difference in price and cabin class, but it is further complicated by the fact that it was an upgrade to both legs, but the other one was a UUA so there were additional fees added there too - I've had to manually unpick this just to work out how much the cash upgrade actually cost.

What do you think the chances are of anyone at BA understanding when they don't think I paid anything in the first place? I'll give it a go but I'm not optimistic. Why they can't just see we were booked into I class, and realise it must be a revenue bucket, is anyone's guess, unfortunately I don't think I have that information anywhere now.

Incidentally there are no admin fees as it was done within 24 hours of the original booking. So no money changed hands at that point, the holiday deposit was already paid and the balance didn't need to be paid for several more weeks.