How to extend my national visa in Poland by one day?
Upvote:2
You have a national D visa which ends on June 30th. So you need a Schengen visa (that means any Schengen visa) for July 1st and perhaps a few days more.
Apply for a Polish D visa. Probably impractical.
Apply for a Polish C tourist visa. Not sure how they will react.
Apply for a C visa from another Schengen state. To do that you would have to have genuine travel plans which take you there after your studies in Poland so that the other state is the main destination.