Lycamobile charged customers mobile call rates for fixed line calls between January 2011 and August 2013, according to the Australian Communications and Media Authority (ACMA).
The UK global mobile virtual network operator (MVNO) overcharged 12,569 customers in Australia by AU$13,387 collectively, over the three-year period, according to a statement published by ACMA today.
"Between January 2011 and 31 August 2013 [Lycamobile's] billing system didn't always recognise the difference between mobile numbers and fixed-line numbers starting with '4'. As a result, 12,596 customers were over-charged a total amount of $13,387 when calling fixed line numbers starting with '4'," said ACMA in its statement.
ACMA said that Lycamobile worked to fix the problem with the billing system, self-reported the matter to ACMA, and moved to compensate customers once it identified the problem. However, it still represents a breach of the billing rules in the Telecommunications Consumer Protections Code.
"Accurate billing is basic to so many aspects — the very efficacy of the TCP Code at one end of the continuum and smart customer care at the other," said ACMA chairman, Chris Chapman, in a statement.
"In this case, we acknowledge that Lycamobile acted quickly and proactively to compensate affected customers."
Lycamobile is the fourth provider the ACMA has found in breach of the TCP Code for failing to ensure accurate billing since the Code came into effect in September 2012.
In each case, however, the provider brought the matter to the attention of the ACMA and worked proactively to compensate affected customers.
Lycamobile, which is a re-seller of the Telstra network in Australia, hasTelstra's 3G products after appearing to escape a in March.
Last year, the company found itself before the Federal Court on claims that it had underpaid its employees by AU$28,000 in total over several months in 2011.