Below is from the independent.
A spokesperson for Comair told The Independent: “The situation arose as two damaged business class seats were not removed from the check-in system, as should have happened. As a result two customers were checked-in and allocated seats in which they could not fly.
These customers were both silver card frequent flyer members, who are prioritised as a matter of global policy. In considering who could be asked to downgrade, the airport staff then identified non-frequent flyers travelling on discounted business class fares. This is common airline practice on rare occasions when downgrades occur. It was on this basis that two other customers in business class were approached