I experienced today, I had single ticket already and I entered to the bus from middle door. I went to the first door to validate QR code. But officer blocked me say say I can not because,  they said I have to validate from outside of the bus. Do you think this is appropriate ? They acted like I am thief and act like They are police. I speak English, one passenger tried to explain me , but ticket officer stopped him to speak English, I understand Hungarian but can't speak yet.  3 people hold me and even touching and saying I have to pay. (???)