I'm not sure if you use credit card or debit card.
However, it sounds like you used debit card.
I have once told from my bank, how they do pending and clear..
They put it on pending, and while they are processing, they will take the transaction away (meaning not even pending nor cleared on your statement) right before it will show on your statement as cleared...
That's the best case scenario. Somebody also posted here a couple days ago about their DF being canceled and it was due to him not having sufficient funds in their checking account that was linked to his debit card. So just make sure you have enough money in there or AT&T might be forced to cancel the DF as they won't be getting paid.