So Which Is It, AT&T?

I'm confused by AT&T's attempt to quantify my data usage under my plan. I am on a family plan with my wife, yet the data that is shown below is supposedly for just my line. I looked at her usage and it's higher than what it shows for me.

Screen Shot 2011 12 28 at 1 21 00 AM

When I pulled up the data usage meter on my iPhone via AT&T's own application, this is the information it displayed:

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Now you can understand my confusion. You would think that if AT&T truly cared about the customer (as we all know they do), there would be an attempt that making sure the usage meters agree with each other to a certain extent. At this point, I'm not sure which set if information is correct, although I'm inclined to believe the iPhone app, simply because I don't use that much data. It begs the question: so which is it, AT&T?