For months, they’ve been shocked by inexplicably high electricity bills and stressed out by disconnection notices. They’ve made major changes to the way they live based on cynical advice, part of what seems very much like an intentional runaround by Central Maine Power. Now they deserve answers.

Those CMP customers got at least one answer Sunday with the publication of an investigation by the Portland Press Herald/Maine Sunday Telegram: No, they are not crazy.

When CMP rolled out its new billing system in October 2017, many customers immediately began receiving bills that were outrageously high. When they complained to the company, CMP blamed cold weather, faulty appliances, or old wiring.

Even when customers say they ruled out everything but a problem on the company’s end, CMP did little but continue to send high bills and disconnection notices. Stuck, customers began taking drastic measures, unplugging unused appliances, and cutting back on showers and toilet use, among others. Customers looked with puzzlement at heavy bills for modest homes, or for places that were not even occupied.

All of them wondered what they were doing wrong.

Well, it appears that those customers were doing nothing wrong. Perhaps a few here and there across CMP’s coverage area could have a faulty appliance, or suddenly use much more power one month to the next without realizing it.

But thousands of customers all affected in roughly the same way, all starting at the same time? Something else is going on here.

An outside audit by Liberty Consulting Group, hired by the state Public Utilities Commission, found CMP failed to properly test its new system and fix bugs before going live. The audit also says the company’s customer service infrastructure was not ready to handle complaints from the rollout.

The audit said CMP’s smart meters, which transmit customer usage data and were an early suspect in the billing problems, were not at fault for the higher bills. The audit instead blames a cold weather snap and rates changes, though it also faults CMP for failing to handle the fallout well.

However, customers continue to report receiving bizarre bills out of whack with reality. Months since CMP told the PUC that its new billing system is working properly, many customers have yet to get a bill that doesn’t raise legitimate questions.

The Public Advocate’s Office hopes to answer them. On Monday, Barry Hobbins, the public advocate, asked the PUC for permission to test the CMP billing system to find patterns among customers who have complained about high bills. He would look at 1,369 accounts that brought complaints since May 1, 2018 – where Liberty’s audit left off – as well as those that have come since April 30.

The tests can look for anomalies between the information taken from the meter and what’s on the actual bill. If problems are noticed, they can be investigated further. The process could eliminate winter cold and supply rate increases as factors, and see what else is going on.

The explanations being offered by CMP now just don’t check out – and as explained in the newspaper’s investigation, the company’s actions in implementing the new billing system have hardly made them trustworthy.

As we said in our Sunday editorial, that raises questions about CMP’s future in Maine.

But more immediately, it’s important that Mainers get clear answers as to why their electric bills have all of a sudden upended their lives.