Michael is one of the remaining unlimited data customers at AT&T Wireless, and got to keep this plan after upgrading to a shiny new iPhone 4S earlier this year. At least he thought he did. When he signed his new contract, he accidentally ended up with some add-ons he hadn’t requested, like roadside assistance and insurance on his phone. He called to remove these, and somehow this resulted in his losing his unlimited data plan and switching to a mere 3-gigabyte one.

He blogged about the experience:

I’ve had one of AT&T’s unlimited data plans since I first got an iPhone 3GS not quite three years ago. You can thus imagine my surprise when I checked my bill last month and discovered that I had been switched to 3GB/month limited data plan.

On the surface, this might not sound like a big deal. After all, both plans cost $30/month and AT&T recently announced that they would throttle unlimited data users who exceed 3GB/month. Nonetheless, I don’t like being switched without permission, and I’m not crazy about the possibility of overage charges with the limited plan.

Since I upgraded to the iPhone 4S back in January, I thought they might have screwed up my plan at that point. A quick review of my contract, however, revealed that I was still (supposed to be) on the “DATA UNLIMITED FOR iPhone W/VISUAL VOICEMAIL” plan. The rep had even highlighted it in yellow. I thus decided to call AT&T and ask for an explanation.

When I finally got a rep on the line, I learned that they had made the change on March 22nd when I had called in about another billing error. As it turns out, when I upgraded my phone, they not only renewed my contract, but they also added roadside assistance ($2.99/month), phone insurance ($6.99/month), and something called the “enhanced mobile protection plan” ($3.00/month).

(note that none of these charges were reflected on my signed contract)

When I called back in March, I had no trouble getting them to remove the unwanted services and credit me for the charges, but… They apparently took this opportunity to also switch me from my beloved unlimited data plan to a 3GB/month limited data plan. Without my permission.

Was this a simple mistake? Possibly. Or are they “migrating” people over from unlimited data plans (which AT&T CEO Randall Stephenson regrets having offered in the first place) if/when they get the chance to tinker with your account? Perhaps.

Either way, the rep happily agreed to restore the unlimited data plan — though she did need a manager to authorize the change. Aside from the time spent on hold, this was an easy fix. In fact, it almost felt too easy. Sorta like they’ve been making this “mistake” on purpose and are ready if/when people noticed and call in to complain.

Putting on my tinfoil hat: The fact that they were already in my account making changes gave them a bit of cover. If I hadn’t noticed the change, they would have succeeded in ridding themselves of an unlimited data plan. And if I had noticed (as I did) they could just chalk it up to human error.

My advice? If you have an unlimited data plan and you want to keep it, pop into your account from time to time (especially after making other changes) and make sure they haven’t taken it away from you — inadvertently or otherwise.

Most likely Michael is being paranoid here. We hope. But it’s always a good idea to log in to your account online or using your carrier’s account-maintenance app (if they have one) after a phone upgrade or an encounter with customer service in order to make sure that your account features are still set exactly the way you’d like them.

AT&T Downgrading Unlimited iPhone Data Plans? [jammer(six)]

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