Hi, everyone. Just want you guys know that I had a problem of large data consumption with my iPhone 6 plus running iOS 8.0.2. I had a chat with Apple Tech support and they ran a diagnosis on my phone and found that an back service app called backboardd was using over 1.5G cellular data over one night. They told me the app is used for apps to communicate with other apps. They asked me to reset my settings to try to solve the problem. And I am going to monitor this. Hope this could help and please pay attention to your data usage. The data usage shows under system -> Media services.