Nearly two-thirds of the incidents involved billing problems. Three major categories emerged: setup and access, including difficulties retrieving statements online or getting detailed call logs; errors, many involving calls made while phones (according to their owners) weren?t in use; and the failure of statements to reflect terms, such as credit or rate-plan changes, negotiated in discussions with customer service agents. When adjusted for size, the worst-performing carrier in the three categories received 3.8 times more billing complaints than the best.