Central Maine Power Co. admitted Thursday that it had another breakdown in customer service last month when it mistakenly informed 62,000 residential electricity users that they would be receiving a credit on their bills.

The message that appeared on bills mailed in late January was intended to be sent only to 122 large industrial energy users who are owed about $3.2 million in overages that were the result of prepayments companies made based on a formula set by regulators several years ago, a company spokeswoman said Thursday night.

“It was the right message sent to the wrong group of customers,” Catharine Hartnett said in a telephone interview. “This was an unfortunate error that stands out due to some of the customer service issues we have been experiencing.”

The blunder is the latest setback for Maine’s largest utility company, which has been under fire for failing to address customer complaints and for failing to issue monthly bills to thousands of new and existing customers. CMP also has been accused of taking too long to address customer complaints.

A scathing letter the Maine Public Utilities Commission sent to CMP President Doug Herling threatened to fine CMP unless it took immediate action. The letter, which was made public Wednesday, said possible sanctions could include a $500,000 fine and the possibility of reducing profits.

The mistake also comes at a time when the company is trying to rally support for its proposal to build a 145-mile transmission line through western Maine that would bring hydroelectric power from Quebec to Massachusetts.

Hartnett said that CMP notified the PUC about the refund miscommunication on Jan. 31.

She blamed the mistake on human error, specifically a computer programmer in the company’s Customer Service Department, and said it had nothing to do with the company’s new “SmartCare” billing system.

Hartnett said no one was harmed by the advisory message, emphasizing that no one in the residential group received refunds and the funds remain available.

PUC spokesman Harry Lanphear did not respond to a message seeking comment Thursday night, but he told Maine Public that he was uncertain what steps, if any, the PUC might take following the company’s latest misstep.

Lauren Loomis, a spokeswoman for CMP Ratepayers Unite, said the miscue adds to the concerns of her group, which was created as a forum for ratepayers who have seen dramatic and seemingly inexplicable increases in their energy bills.

“It was strange (the refund promise) and it was misleading. It’s just another concern to add to the growing list of concerns,” she said. “These errors keep popping up and there are no explanations being given.”

The group, on its Facebook page, says it wants to hold CMP accountable for “the unjust overcharging of their ratepayers.”

Portland-based attorney Tony Buxton serves as general counsel to the Industrial Energy Consumers Group, a group of large industrial and commercial energy users that monitors and participates in the development of utility regulation policy in Maine.

Most of his clients will be receiving a chunk of the $3.2 million in overages.

“Believe me, no one is getting rich on this,” he said.

Buxton said news of CMP’s latest error is disheartening.

“What we want is a strong utility that can help everyone with the challenges of daily life, but this continuing barrage of unfortunate events is very concerning to all of Central Maine Power Company customers,” Buxton said Thursday night. “It’s a big distraction that just should not be happening.”

Hartnett said the 62,000 residential customers who received the bill credit message will get a note in their next bill notifying them that no refunds will be made.

Dennis Hoey can be contacted at 791-6365 or at:

dhoey@pressherald.com

.