At&t
AT&T seriously needs to turn things around. I have been a huge iPhone supporter since it was first announced. I was one of the guys who waited in line on launch day, and AT&T has me seriously considering the competition because of their service!
I recently went overseas and before that did research into the cost of using my iPhone there, I ended opting for their $200 package for 200MB of data, figuring there was no way in hell I'd use that on a 10 day trip.
4 days before I returned I get a text message stating that I am approaching the limit. (I reset the usage meters on the phone before I landed in Europe), so I checked it, and it said I'd used 80MB.
Then the day before I returned I got a text saying I'd gone OVER, I turned my phone off (This is not tethered NOT Jailbroken). When I landed in the U.S. I saw that my usage was well under the 200MB limit, but when I called AT&T to talk about it they said I was well over the limit. I had to argue with them for WEEKS. I had screen captures of the usage on a day-by-day basis.
And they actually threatened to turn my service off when I refused to pay what they say were the overage charges!
They finally DID reverse the charges, which is great and wonderful, but I spent a lot of my time arguing with them about it, and had it not been for me vigilantly checking my usage and taking screen captures I would have been royally screwed by them.
AT&T sucks for many, many reasons and Apple needs to come to their senses and realize they've become a major liability in the U.S. to the Apple Brandname.