I have an iPhone 4S with 7.1.2 software and I can't stream music on 3G anymore. The song either doesn't start or if it does start then the song freezes after a few seconds.  Never had this problem until about 2 weeks ago but now I can't play Spotify in my car or when walking around without the music freezing after a few seconds.  I don't have problems playing Spotify on my iPhone when I'm connected to wi-fi so it's only a problem when I'm on 3G.  

I've tried deleting and re-installing Spotify on my iPhone.  Didn't fix it.  I've tried restarting my iPhone.  Didn't fix it.  Does anyone know how to resolve this issue?