The Maine Public Utilities Commission on Monday rebuffed the public advocate’s call for an elevated investigation into hundreds of inexplicably high Central Maine Power Co. bills.

The PUC said it will continue its deliberative examination process and not elevate the case at this time.

“The commission’s summary investigation of CMP will be thorough and comprehensive,” said PUC spokesman Harry Lanphear. “(At its conclusion), the commission could elect to open an adjudicatory case to more fully explore any aspect.”

An adjudicatory case would allow regulators to punish CMP if the company is found to have violated state law.

The decision follows reports last week by the Portland Press Herald that CMP had known since October that its new billing software had multiple problems affecting thousands of customers, although those glitches haven’t been directly linked to the issue of high bills. Details about the problems and efforts by CMP and its parent company, Avangrid, to find solutions were contained in hundreds of pages of internal emails posted on the PUC’s website. After seeing those emails, Public Advocate Barry Hobbins called on the PUC to change its review from a summary investigation relying largely on data requests to a so-called adjudicatory case.

Lanphear, however, said such a move is premature.

“Should there ultimately be a finding that CMP failed to provide safe, reliable and adequate utility service as a result of our investigation,” he said, “in addition to refunding any affected customers, the commission could issue an administrative penalty … and/or direct the utility to take specific actions that remedy any service inadequacies,” among other actions.

Hobbins was disappointed by the PUC’s decision, but not deterred.

“That’s their decision,” he said. “But I’m going to keep the pressure on and the pedal down to keep this in the forefront. I just wish they would be more proactive. I think ratepayers need full attention and immediate action.”

Monday’s exchange is the latest development in the mystery of what caused hundreds of CMP customers to report high bills, beginning in November.

More than 250 pages of documents, some marked confidential, were reviewed by the Press Herald last week. They showed persistent problems with CMP’s new billing system, a situation that got scant mention in early April from a top manager, who said the new billing system was not contributing to extraordinarily high bills for some 1,500 customers.

The internal documents portray a company desperately trying to understand problems with its new billing system and how to fix them. CMP switched from its 27-year-old mainframe computer system on Oct. 30, 2017 – the day a powerful windstorm knocked out power to more than 400,000 CMP customers.

The documents filed with the PUC are available to the public on the agency’s website, but are difficult to find in the thousands of pages generated so far in the case. The problems they describe include:

• Customers who paid their bills with an auto-pay feature were being unenrolled from auto-pay.

• Some customers saw double usage on their bills, but zero cost.

• Some net energy accounts, such as customers with solar panels, had very high estimated bills.

• SimplePay customers, who pay the same amount each month to smooth out their bills, were dropped for minimal non-payment.

• Bills couldn’t be seen on iPhones.

The documents also show that staff from CMP and companies affiliated with Avangrid made diligent efforts, racking up overtime and working weekends, to track down complex software errors.

The exchanges between CMP employees called into question some assertions made last month by CMP’s top management about the high bills. In a conference call with reporters April 6, CMP President and CEO Doug Herling said the company had reviewed about 25 percent of the 1,580 complaints of excessive bills it received over the winter and its internal audit found no problems with the company’s systems that would explain the unusually high spikes in some customer bills.

“We have done our investigation. At this point in time we have not found anything about our system or smart meters that would artificially increase customers’ usage,” Herling said.

CMP has stuck with that contention, and has said reporters on the conference call may have missed discussions that acknowledged bugs in the software, but that the glitches weren’t related to high bills. A CMP spokeswoman said the company does not have a recording of the call.

On Monday, the spokeswoman, Gail Rice, reiterated CMP’s desire to see the investigation to its end.

“We’re committed to working cooperatively with the commission in all aspects of its investigation into CMP’s metering, billing and customer communications,” she said.

Hobbins, however, insists CMP should have been more transparent about any problems and coordinated a response with state officials. He said CMP representatives “should have met with me, the PUC, the Governor’s Energy Office and said, ‘Can we all work together on this?’ ”

Lanphear, meanwhile, said the commission’s staff is still reviewing and assessing high volumes of data received from CMP, a process that will take time. The PUC also is close to selecting a private consultant to conduct a so-called forensic audit of CMP billing, customer service and meter systems. This entire process is expected to take until the end of the year.

“The next step is likely to be follow-up questions and information requests by commission staff,” Lanphear said, “which can occur in writing or through an in-person conference.”

Maine Public Advocate Barry Hobbins