I have a limited 3G plan on my iPhone 4S and I also have iTunes Match service.
In order to keep the phone from downloading songs from iCloud, while under 3G connection, I had set 'Settings>Store>Use Cellular Data' to OFF. This seemed to work just fine until I downloaded the iOS 5.1 update.
A couple of days ago I was surprised to find that while listening to shuffled music, I had ran out of credit because the Music App had been fetching songs from iCloud using 3G, even though the Setting was still OFF.
I've been forced to turn off my 3G every time I want to listen to music on the go, which is really annoying.
Is this a known bug? Is anyone else experiencing the same problem? Is there a fix?