How to send a complaint

I would like to write to SAS to complain about their boarding procedures — forcing us to stand in this cold air bridge for 20m — but I can’t find an email address anywhere. The stewards told me (repeatedly) that you leave a message on the app but I don’t want to get the app (as I told them repeatedly).

Grateful if anyone knows of one, and isn’t it crazy that companies no longer think that receiving complaints is something they need to do.