For these cases when your flight is cancelled or the time of the flight changes, you can use the Autoprotección service which allows you to see the other available flights for your route and choose the most convenient one.

https://www.latam.com/es_ar/apps/per...utoproteccion/

There used to be a chat but it is not available any more.

You may be able to choose a flight with business class available on that web page.