Most window washers work daytime hours.
Did you ask any of your neighbors for recommendations recently?
You might ask your neighborhood who they use for cleaning windows, as it is typical for these types of home services to try to promote themselves within a neighborhood once they have gotten on client in the neighborhood, and they often don't look at the Do Not Call list.

My neighborhood association has a Yahoo Groups listserve and one person recently asked for recommendations. One elderly couple has a housecleaner who cleans the windows on the outside about twice a year. That housecleaner has never asked me if I wanted her cleaning services.