There are an estimated 76,000 customers who may be due refunds
Eircom has been hit with a 2.45 million euro penalty for overcharging customers.
The company, now known as Eir, will refund customers and also make changes to its billing practices.
The Commission for Communications Regulation took enforcement action against Eircom and says the company has committed to paying a 2.45 million euro penalty.
Eir's also implementing a series of 'backward looking measures' , where it will identify customers who were incorrectly overcharged historically and have not been refunded.
There are an estimated 76,000 customers who may be due refunds, valued at 6.7 million euro.
The focus will be on customers incorrectly charged due to a broken bundle on the customer's account and where customers were charged after requesting the end to their service.
It'll also look at those who faced early cease charges when they were allowed to cancel without payment.
The company will appoint and Independent Auditor to review the effectiveness and implementation of the measures.

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