Not entirely relevant to your post, but mine does seem to have a mind of it's own. The phone says it has used 9GB in the last 5 days, but AT&T says I have used 4GB in the last 10 days. I tend to believe AT&T because they have money riding on it. The data usage screen shows Edge has used 2 GB and everything else combined comes to less than 100MB, so I don't know where it is getting 9GB from. I have all background data disabled and am not a heavy user.
AT&T shows about 90MB transferred at 5:45am today, at which time I was snoring loudly (most likely), so that's weird too. It's kind of messed up that you have no way of knowing what data you are really using, especially when you are paying for it. The bill just shows a time and an amount of data, but that's pretty useless. You have no choice but to believe the carrier.