The Australian Communications and Media Authority (ACMA) has sent a formal warning to local telecommunications giant Telstra Corporation Limited since it breached the Telecommunications Consumer Protection Code (TCP Code) , which requires providers to bill customers accurately, to overcharge customers for using data services on their mobile phones while overseas, ACMA announced through a media release on Monday. According to the ACMA, Telstra self-reported to the watchdog organization in November 2012 that it had overcharged just over 260,000 customers a total of around 30 million Australian dollars (27.72 million U.S. dollars) for international data roaming between 2006 and 2012. Although most customers were overcharged small amounts, the telecommunication company has incorrectly billed a large number of international data roaming customers multiple flag fall fees for single data sessions. The company explained that the incorrect information it received from its international carriers and contracted data clearing house caused those inaccurate bills, the media release said. However, Telstra did not investigate the problems after receiving a complaint from a consumer who had been incorrectly billed for multiple overseas data sessions in early 2009. \"While they had a very small number of complaints, they didn\'t try to look to see whether there was a systemic problem. They only decided to look at that in 2012,\" Chris Cheah, full-time member of ACMA and former head of the Telecommunications Division of the Department of Communications, Information Technology and the Arts who gives advices to the Australian Government on the full range of telecommunications issues told local media ABC News. The ACMA investigation found that billing inaccuracies after that complaint were caused by Telstra\'s failure to investigate and identify the problems with the information being provided by its contractor. But the ACMA decided to only present a formal warning to Telstra this time since Telstra was not the original cause of the problem and reported the problem itself. Once the information problem was discovered, Telstra promptly identified all customers who were incorrectly charged for international data roaming and is systematically providing rebates. It has also permanently ceased charging a flag fall fee for international roaming data services, the ACMA\'s media release said. Telstra also proactively implemented a comprehensive program of compensation to comfort the harm for affected customers, ACMA said. \"Once they realized there was a problem they acted on it fairly quickly and tried to rectify it, and moved to compensate customers, so they\'ve dealt with it in a fairly good way.\" Cheah told local media. \"We also proactively notified the ACMA and began a process to fully refund customers and to apologize for this happening in the first place. We have permanently removed the charge in question and we accept this finding from ACMA,\" Telstra replied the warning in a statement. \"Accurate billing is of the utmost importance. Our investigation makes it very clear that all telcos need to listen to their customers who report billing problems and be vigilant about any potential issues with the information provided to them by third parties,\" said ACMA\'s chairman, Chris Chapman.