What can be done about fake monks?
I have some suggestions. 

Guard yourself against any possibility of Wrong Speech by not saying anything about these persons, their motives, or actions that you don't personally know to be true; even if it seems extremely likely that they are being deceptive. If you want to warn family &amp; friends, stick only with what you know to be true such as "In the tradition I study, monastic rules don't allow monks to ask for money or sell good luck charms."

Guard yourself against the arising or continuing of any negative states by not identifying with this issue. This is not personal. Cities have always been magnets for people inclined to do "creative fund raising". ;-) City dwellers are pretty savvy about this type of thing and it's unlikely the media will downplay it indefinitely. It's too quirky of a story for them to ignore forever. 

Guard yourself against the attachment of "me and my" Buddhism getting a bad name. Truly awful things have happened in the contexts of other religions; bloody wars, sexual exploitation, financial scandal. 

The teachings of the Buddha shine on. A little thing like this can't tarnish it. :)