New Brunswick's Energy and Utilities Board has launched a formal investigation into Irving Oil Ltd.'s billing practices following CBC reports of the company charging some customers more than the province's maximum price for furnace oil.

"The board is looking to the issue of overcharging," said EUB spokesperson Dave Young. "The board on its own can issue a notice telling the company not to overcharge customers or it can recommend charges to the Crown prosecutor."

Corey Duke of Saint John contends Irving Oil has overbilled his grandmother at least $384.84 for home heating fuel by charging her as a commercial customer. (CBC) $195 more than the maximum price for furnace oil on a delivery last Wednesday. Last week, CBC News reported that Irving Oil had charged Fredericton librarian Joanne Smyth

The company had wrongly listed Smyth and her husband as a commercial account and said those customers were not entitled to the protection of New Brunswick petroleum pricing laws.

Smyth said they were told by an Irving Oil representative the company had "wiggle" room with commercial customers to charge beyond provincial maximum prices.

That was also the explanation given to Saint John resident Corey Duke when he complained about his grandmother being charged more than the maximum price by over $130 on a delivery last Tuesday.

There is nothing in the act — the Petroleum Products Pricing Act — that specifically exempts commercial customers from the act. - Dave Young, Energy and Utilities Board

Duke's grandmother lives in a building that has two rental units and Duke says an Irving Oil representative said that exempts her from regulation.

"She told me outright that commercial accounts are not subject to the Energy and Utilities Board," said Duke.

But Young says there is nothing in New Brunswick petroleum pricing laws that separates the way companies can treat commercial and residential customers and the board has asked Irving Oil for more details on its billing practice.

"The act applies to consumers and there is nothing that specifies what kind of consumer it is," said Young. "There is nothing in the act — the Petroleum Products Pricing Act — that specifically exempts commercial customers from the act."

Smyth eventually found 27 bills dating back to 2010 where she had been charged more than maximum prices, while Duke says it happened to his grandmother 13 times in her last 15 deliveries.

Irving Oil has agreed to repay Smyth more than $700. Duke says the company is still evaluating billings to his grandmother and what if anything to refund her.

Samantha Robinson, a spokeswoman for Irving, said the company has become aware of several customer concerns around billing for heating fuel.

"As soon as we became aware of this issue, we launched a thorough review and discussed this matter with the EUB. We expect our review to be completed shortly, at which time we will share the results with the EUB in full cooperation with its request that we do so," she said.

"Irving Oil highly values its relationships with its customers and does not take them for granted. Where there has been an overpayment, we will sincerely apologize and fully reimburse them for such amounts."