I'm surprised: usually services like that are pretty careful about the properties they are working on, because the property owners often object to this kind of thing.

A word to the building management, perhaps?

I'm with Jonathan. Talk to the building management.

I finally nerved myself up (confrontation is so not my thing) and made a joke at one woman armed with a hammer and a four-inch nail. She swears they do the building's decorations every year and that they always nail stuff to the railings. She seemed to think it was okay because "it's on the outside, where no one can see it."

I had a moment of cognitive dissonance--what is it with the attitude that it's not damage unless you can see it? We live in such a disposable society....