A scathing state report says Frontier Communications may have violated at least 35 Minnesota laws and regulations, failing its customers with shoddy service, lax record-keeping and inadequate investment in its own network.

Frontier said in a statement that the company strongly disputes the report, which was issued Friday.

The investigation by the Minnesota Department of Commerce was commissioned in March by the Minnesota Public Utilities Commission (PUC), which had been flooded by complaints from Frontier’s patrons. Frontier has about 90,000 customers in Minnesota, and the PUC regulates the company’s phone service.

“The findings of this investigation detail an extraordinary situation, where customers have suffered outages of months or more,” the Commerce Department concluded. Also, Frontier “systematically refuses” to provide refunds for outages, which “plainly” violates state law. Some of those service outages hit Frontier customers with urgent medical needs, including those with pacemakers monitored via landline phone service, the report said.

Also, Frontier’s record keeping “appears to have become so deficient” that for some “critically important data” — including the duration of outages — the company’s records cannot be relied on, the report said.

In addition, the Commerce Department noted “stunning” deficiencies in Frontier’s physical network due to the company’s “failure to keep its plant and equipment in a good state of repair.”

Frontier customers reported broken equipment — sometimes with exposed wiring — and unburied phone lines.

Frontier “strongly disagrees with the assertions in the Department of Commerce’s initial comments and is reviewing the Department’s filing,” the company said in its own filing.

“Frontier recognizes we experience service issues and delays from time to time with some of our customers,” it said. “We are an ethical company committed to our customers and the Minnesota communities we serve. We take this matter seriously and will respond appropriately before the Public Utilities Commission.”

The PUC will weigh the report in taking any regulatory actions against Frontier. The report recommends that the PUC require Frontier to refund or credit customers for service outages and unauthorized charges; add staff to improve customer service; and increase investments in infrastructure and equipment.

Stamford, Conn.-based Frontier operates under the Frontier brand and Citizens Telecommunications in Minnesota. Many of its customers live in rural northeastern and southern Minnesota, though the company also covers parts of Farmington, Apple Valley, Rosemount, Lakeville and Burnsville in the metro area.

Frontier said in a statement that it provides “reliable, affordable” service to its Minnesota customers, many of whom live in “rural communities where no other provider will invest in providing service.”

Frontier is a publicly traded company with operations across the country that generate around $9 billion in annual sales.

The PUC began looking into Frontier last winter after hearing from its customers about poor service, from static-filled phone conversations to billing snafus.

The PUC ordered seven public hearings across the state. Between the well-attended hearings and missives sent directly to the PUC, there have been over 1,000 complaints about Frontier.

The Commerce Department report said that 400 complaints about Frontier concern phone and internet service as a bundled package, while 250 focused on phone service only.

Another 325 complaints were about internet only.

The PUC only regulates landline phones. Federal law generally prohibits state regulation of internet service.

However, the Commerce Department report said Frontier’s internet and phone service are often tied together in Minnesota.

“In many cases, Frontier’s provision of internet access service … interferes with Frontier’s provision of voice service, and vice versa.”

In other cases, Frontier’s “failure to employ sufficient resources” to provide phone and internet service has resulted in long and repeated outages, involuntary disconnects, poor service, billing-related complaints and “negligent or fraudulent representations of internet quality,” the report said.