A further comment on the same subject. I recently bought a mileage earning World Special round trip from Geneva to London Heathrow. On the return journey, I upgraded to C-class at check-in at Heathrow, against 5,000 miles. Normally, I should collect 1,000 economy club miles for that trip, but my online statement shows it as Z class "Fare not eligible for mileage accrual". Does upgrading in such a manner take away our right to collect miles according to the fare paid, and what should I do?