Study / Delayed Arrival in Warsaw university of Technology [8]

Hi everyone, I am really stuck up In this dilemma and I had like some suggestions from people, I am an international student of Warsaw university of technology, the last arrival date was 14th October but the visa took time in processing and I got my visa starting from 20th of October hence I booked the tickets on 20th to Warsaw. I messaged the university that I would be late but the university clearly denied that my application is now invalid as the last date of arrival was 14th October, my visa is valid only for 3 months so I planned to go to poland and get a temporary residence card but now I can't do that either. I have my flight to poland in 2days, what do you suggest I do ?