The auction upgrade system is used by several airlines
http://www.plusgrade.com/
https://www.latam.com/en_us/plan-boo...et-an-upgrade/
This service is not available on these routes:
Santiago - Sao Paulo.
Santiago - Río de Janeiro.
Buenos Aires - Sao Paulo.
Bogotá - Sao Paulo.
Lima - Sao Paulo.
Another
https://www.optiontown.com/home_page...=SelectProduct