So, hypothetically, what should I do?

[Oregano]

If this fails, I recommend a pitchfork and a mob.

You forgot the torches, for shame.

I agree that it might be an isolated thing but if they'd just do that I'd watch out for them in the future, from initial impressions they seem a rather unsavioury bunch.

If they are scumbags it might not be best to confront them because they might get scumbaggish.