How do I prevent Music app from using 1 GB of cellular data in less than 10 minutes?

I received 3 text messages within 10 minutes from my cellular carrier as I was driving in my car with iTunes Radio streaming music.

1. 10:20 pm - 65% of my 1 GB plan is used.


2. 10:22 pm - 90% used.


3. 10:28 pm - 100% used and a $20 fee for going over. The music got jumbled up at this point. It would play a split second, pause, and repeat.

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I went into Settings > Celluar to find the culprit. It was indeed caused by the Music app, so I immediately switched off its cellular usage. It had used up 1 GB in 10 minutes. This was the first time I attempted music streaming while driving.

In all the articles that I've read, they say iTunes Radio should only use 28 MB per hour - much less than what I just experienced. So what caused my meteoritic rise in data usage?

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The following screenshot shows that I have no local music collection, so the phone couldn't have been synching any music from the cloud. That infamous free U2 album that was uploaded to everyone's phone is not on my phone.

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More info:

• Background app refresh is turned off.


• iOS 8.1.1


• iPhone 6


• Music settings: "Genius" off. "Show All Music" off.