No one likes being ignored by their. friends, especially when they need help. It sounds like you need to find some new friends; not some self-involved fair-weather friends.
I wouldn't go to extremes by changing your number, since they are the ones who are ignoring you. If you feel strongly about it, then simply block them. The same goes for FB. You can't be mad a friend for not logging into FB. I go weeks without logging into FB. However, if you no longer consider these people your friend, then simply "unfriend" them.
I hope I'm not coming across as cold, because I know it hurts. I also feel that your feelings are valid. They are your feelings, not to mention that people tend to be more unaccountable for the way they treat their friends these days. I just wouldn't go out of my way to change my phone number, FB and email due to their behavior. They aren't worth the trouble. I also think I'm probably more jaded than you are, since I have very little expectations of people at this point.

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