I’ve been trying to find the title of this movie for some time now, and every keyword I type into Google hasn’t brought much help yet. Hopefully someone here has seen it?? (fingers crossed). I saw this movie a while ago, so the specifics are fuzzy, but from what I can remember:
A young man is held in his home by these kidnappers who have threatened to kill his girlfriend if he doesn’t comply with their wishes. They inform him of what he must do via letters, so it’s interesting that you don’t see who they are. I remember he must board up the windows and pretend noone’s home. He also makes a chart, as he’s given a daily ‘allowance’ of a certain amount of points (I believe it was 7) he uses for things he needs-- food-2 points, water-3 points. In 1 of the scenes, he goes hungry in order to pay for his girlfriend to be there with him, and she tells him they’re treating her very well.
I saw the movie The Ceremony (in that movie, the man in the house can’t leave until he does the ceremony as demanded/described in this ancient book), and this movie is similar, but different.
Here’s hoping someone has either seen it, or has a better search engine (or keywords/ideas) than I do. GREATLY appreciated 
What year did you see it? Did you see in a movie theater when it was released or in a theater long after it was released or on TV or on DVD or videotape or what? What country was the film made in? What language was it in? Was it color or black and white? Was any actor in the film recognizable? Did it look low-budget?