Rupture (1961)

When picking up his mail, a man is excited to see a letter from his sweetheart. His excitement turns to sorrow when he gets home to his flat and sees that it is a Dear John letter. But that sorrow turns to anger as he figures that he will send her a Dear Jane letter in return. However, writing that letter isn't as easy as he hopes as he encounters one problem after another, from a broken fountain pen, to a temperamental ink well, to stuck stamps, to a broken desk.