The Commerce Commission intends to file court proceedings today against Spark under the Fair Trading Act.
According to the watchdog, the action is in relation to three separate historical operational and billing issues.
Specifically, these are: an equipment fault in 2015 that affected data billing for a small percentage of customers; incorrect implementation of a "welcome credit" when joining Spark for some fibre broadband customers during 2016; and a billing implementation issue relating to a 30-day notice period when customers left Spark.
Spark told shareholders these were all system-based errors caused by genuine mistakes with no malicious intent on the part of the telecommunications giant.
"In respect of all of these issues, Spark has already applied credits to the accounts of all impacted customers and has made extensive efforts to return all amounts owed to former customers," a Spark statement read.
"While Spark has already refunded many of these former customers over the past 12 months, it has been seeking to reach more of them as part of its 'Make Sure You Get What’s Yours' consumer campaign launched in May 2018.
"Through this campaign, Spark has so far returned over $1.1 million to customers in credits owing, relating to a wide range of circumstances, not just the 30-day billing issue."
Spark also made donations in 2017 to various charities totalling approximately $268,000, in recognition of the interest it was likely to earn on unclaimed credit balances arising from the 30-day billing issue.
Spark said it will review the Commission’s proceedings and has yet to determine its position.
Although the Commerce Commission has outlined the maximum possible penalties available under law for each of the charges, Spark says it has not yet advised the penalties it will seek.
"The decision as to actual penalties will ultimately be one for the court, however these proceedings are not expected to have a significant effect on the financial position or profitability of Spark," it said.
There is, therefore, no change to Spark’s existing 2018 guidance provided in May.