The Commission for Communications Regulation (ComReg) has demanded that Eircom provide it with a full report into the overcharging of customers for services including call-answering, barring and diverting.
A report in today's Irish Times said ComReg had called on Eircom to outline how the mistakes arose, why internal safeguards failed and what steps the company had since taken.
"It is disappointing that the largest telecoms company has discovered that there were errors within its billing system," commissioner Ms Isolde Goggin was quoted as saying. "ComReg is seriously concerned that internal systems failed to adequately protect consumers."
She added that recent incidents of telecoms companies overcharging customers had undermined consumer confidence in the accuracy of their billing systems.
Eircom revealed yesterday that it will refund €409,000 to 31,562 customers who were overcharged for services including call-answering, barring and diverting.
Eircom found that 18,291 customers who ordered call answering free of charge were incorrectly billed for the service. They were overcharged by an average of €1.57.
Individual customers were overcharged by a maximum of around €350, while the smallest amount was under €1. A statement said that the total amount involved was €409,000.