I know how you feel. I'm studying abroad and before I left my friends promised to keep in touch and visit me. Guess what, they have done neither. I have made ALL the effort. When I wanted to meet up with them I had to go to where they would be at Christmas, and even then one b*tch decided it was too much effort to see me for one night and that she'd rather be with her boyfriend. I don't consider her a friend anymore, that's unforgivable in my book, mostly because she had kept promising to meet up. She didn't even have the balls to be honest.
What annoys me the most is they keep making excuses by saying they have loads of work, as if I don't!! I have the same requirements as them only the extra stress of doing it all through a foreign language, meeting new people, moving to a new country, etc! Most of them live at home and don't even have to do their washing! I know they don't mean to be so rude but they just have no idea of what it's like to even live away from their parents and no concept of what 'busy' really is. You can ALWAYS make time for your friends.