Spark estimates the draft pricing will increase its input costs by $60 million and if the decision stands, will materially lift the company's costs and have a negative impact on its 2015 earnings. The company has previously said it's too early to adjust guidance for low single digit growth in adjusted earnings before interest tax, depreciation and amortisation from $936 million in the 2014 year, and didn't update the forecast today.
The company said it's still unclear as to whether the regulator will backdate the new pricing, and if it decides to do so, Spark's higher prices won't fully cover the increased wholesale costs.
"Once we have a clearer view on the final decision on wholesale charges and whether these charges will be backdated we will review the situation and we will do the right thing by our customers," Quin said.
Spark dropped its prices as part of its transformation into a digital services business under the stewardship of Simon Moutter, who wanted the company to compete more aggressively in broadband to stop customers from leaving simply on price.
That competition has seen prices drop for customers, and since Chorus was carved out of Spark, then Telecom, in late 2011, consumer prices for telecommunications services have dropped 10 percent, according to government figures.
In August, Quin told analysts retail service providers had already cut prices in anticipation of a lower regulated price on the copper lines, and that there wouldn't be any further reductions for consumers.
Shares of Spark last traded at $3.03, and have gained 31 percent this year. The stock is rated an average 'hold' based on 10 analyst recommendations compiled by Reuters, with a median price target of $2.83.