tough with them that seems to be the only language they understand and being foreigners they should have respect for the culture and ethos of the country where they are guests.
Yes, what they did was EXTREMELY rude and also wrong!
However, isn't being disrespectful and inpolite to guests also rude? So then, why are you suggesting it? Bei ng that you call them "guests".
Maybe they're not guests though. Maybe they're permanently here. In that case, learn to live with it. Plain and simple. You're not always going to like the chracteristics of your neighbors. But you have no choice who your neighbors are. And you have no control over their characteristics. So what is more valuable to you? I would choose to be friends or at least friendly, accept what I don't like, try to correct any problems before they blow up, etc. This problem already seems to have gone too far. And I feel the rudeness of the neighbors is to blame. But this is about resolution of the problem, correct? Not building more animosity.
Stealing or harming me or my family is where I draw the line and then I would call the police.