While calling is still the preferred method that Southwest recommends to resolve resolutions, there are alternate methods. I am surprised they could not help you on Facebook messenger. I have an ongoing DM with Southwest on Twitter and whenever I have a problem with a flight I pull up the message and write my latest inquiry - I always get a response that way - and almost always same day, if not within hours. They've changed my flights numerous times - but always in advance of the flight, I have never tried it en route or within 24 hours of a flight.
--Jessica
