A very intersting concept- rescoring a clip like that. I like your opening theme- but I thought there were parts where it seemed like the action wasnt being refelcted in the music. Like the first time she answers the phone- there wasnt any change in the music.
There are three things I always keep in mind when writing scary music: maybe they'll be usefull to you. 1. Anticipation/silence: people are afraid of the dark, and people are affraid of silence. For a cheap trick you can always throw in a subito FFFFFF to make people pee themselves. 2. Disorientation: Just my way of saying that wierd tonality throws people off base, and makes them naturaly uncomfortable. A friend of mine swear by 12-tone as a means of evoking fear. 3. The unknown: it's a well known fact is that this is at the basis of most fears- the same applies to music. I always try to throw in wierd instrumental techniques that people wont know what they are- not to mention extra-musical sounds. Think about things like that wierd creaking sound in chain-saw masacre, or freddie's claw scraping noise- that scares you because your not really sure what it is in the begining, and your mind is saying, "wtf is that, and what's it going to do to me?"