I was not able to find out what happened, but it is quite bad that Sixt lost its franchisee in Chile. The leasing company who rented on behalf of Sixt just started their own short rental operations, just had contact with the former lovely staff and I can assure all, their cars are really nice !

https://gamarent.cl/ in Spanish only

And as a bonus, it got cheaper and they deliver cars in Santiago metro area or you can pick up at the airport.

Given the extremely poor choice of cars (no German brands) of the competitors I wish them well.