The computer problem was repaired after the glitch was discovered; it should not recur, according to a spokesman for AT&T. No details about the nature of the problem would be revealed, he said.

"It was an isolated problem and was remedied," the spokesman said. The double billing occurred on Jan. 16 and 17, and customers' accounts are being refunded the amount they were overcharged.

Jacquilin Porter, an AT&T/Cingular customer in Inkster, Mich., said she was a victim of the double-billing on two separate accounts she holds. Because both accounts were double-paid, she incurred bank overdraft charges, which she wants AT&T to repay. The overbilled amount was paid back to her bank seven days after the money was withdrawn on Jan. 17, she said.

Porter, a customer of AT&T/Cingular for nine years, said she was concerned that she only learned about the problem from her bank, not from AT&T. "I feel they are handling this the wrong way on many levels," she said. "I'm concerned about how this happened, why there was no disclosure [and] why they need to have your bank account information to correct the problems they have caused."