As the Next G network was only launch in October, the problem affects almost every Next G bill issued to date. A Telstra spokesman said the company is prepared to refund affected customers' excess data fees, if they call Telstra to complain.

"By far the vast majority of customers wouldn't use 50MB through their phone," he told IT Wire.

"Those who do, when their bill comes in they can phone Telstra and get the excess charges credited back to them."

Customers contacting Telstra to complain of receiving excess data charges without warning during their first three months have been initially told "it's not up to us to notify you when you've passed the limit". After further pressure, some customers have been offered a 50 per cent discount on their excess data charges without an acknowledgement of the problem.

Despite launching several months ago, until recently users of Next G couldn't tell how much data they'd used by checking network's WAP portal. Users were presented with a breakdown of their usage for each time they had accessed the internet - a list up to 10 pages long - but no grand total. A total usage graph has been introduced this month, but customers have reported inaccurate readings. Staff at Telstra call centres are unable to calculate customers' exact data usage figures, making it extremely difficult for customers not to exceed their monthly limits.

Telstra has some of the country's highest excess mobile data charges - ranging from 25 cents to $5 per megabyte, which includes uploaded data.{moscomment}