How is it "brutal Hellenisation"? Do they track down and arrest anyone who doesn't speak Greek?
Well, if you happen to pass trough a Greek village and speak for example Macedonian, Vlach and Turkish, there is a chance you would be escorted by the police to the station and your anything you confiscated that the police would label "as a threat to the state", even if it is just for example a book in the aforementioned languages or a photo-camera.
In the past, and some say even today, if Macedonian or Turkish children accidentally say something in their native tongue in school teachers would wash their mouths with castor oil or send them to the corner. In the past, some 40-30 years ago children would also get some good ass-whipping on top of that.
Stoning and vandalizing of property is not uncommon. Neo-Nazi activity is tolerated by the police and the police themselves commit crimes against members of other nationalities, like when they shot the guard in the US embassy in Athens. When members of ethnic minorities are being beaten by Greek mobs, the police usually just stand around and then threatens the victim for causing trouble. Several such incidents happened in the last few years. And lets not forget Greek Orthodox clergy constantly calling for wars against Macedonia, Bulgaria and Turkey. They would also call against Albanians but these make a half of Greece's population. Most Greeks speak anything but Greek at home. Greeks have many complexes and their government of course uses them for itd own gain.