A $50.7-million hydro bill sent to the Canadian Forces military base at Garrison Petawawa, Ont., last summer is just one of many examples of inflated, miscalculated or undelivered bills cited by Ontario's ombudsman in a new report that looks at Hydro One's billing practices and customer service.

Ombudsman André Marin released his report on Monday saying Hydro One "lost sight of its public interest purpose" and failed to consider the effect on its customers of a new information system that resulted in massive billing errors for about 100,000 households.

Marin said his office was flooded with 10,700 complaints from Hydro One ratepayers about billing issues and what he calls "outrageously bad customer service" as it scrambled to fix technical glitches with the new system.

The report highlighted a major error when Hydro One issued a bill to Garrison Petawawa for $50,747,089.25 in June 2014, with the payment due on July 8, 2014.

That would amount to 11,277 times the normal monthly bill, usually in the $4,500 range, according to the military base. The base receives several different hydro bills each month, a spokesperson said. The base on 300 square kilometres has 587 buildings and 22 more being developed, according to the Canadian Forces website.

Garrison Petawawa, about two hours northwest of Ottawa, wrongly received a $50.7-million Hydro One bill in June 2014, according to the Ontario ombudsman's report. (Garrison Petawawa Imagery Dept.)

The base wasn't the only major institution stuck dealing with Hydro One billing errors. The Globe and Mail initially reported the saga of a ski club that first received a $37,000 bill in error. The Beaver Valley Ski Club was told it was being fixed, but the next bill came in at $37 million, the ombudsman's report said.

Another business received a $15-million bill when it actually owed $4,034.47.

Marin told CBC's Evan Solomon that problems arose when Hydro One's new billing system was rushed into implementation "without a Plan B" to fall back on if it didn't work as intended.

"The whole thing went off the rails, and they just had no customer service plan to deal with it," he said.

Customer billed for gold mine electricity use

Marin's report provides detailed examples of customers who struggled with customer service, including one man who said in the report that he felt "anxious, without a voice, frustrated and bullied" after dealing with Hydro One over a $45,000 bill package that covered a three-year period, including a period he'd already paid for.

Hydro One eventually contacted the Schumacher, Ont., man, the report said, and he was "astounded to learn that because of a mixed meter issue, he was being billed for electricity used by a nearby gold mine."

His charges were eventually dropped to $9,723.04 and he got a credit and a repayment plan, the report said, but he was then hit with two more large bills — one for $12,000 and another for $15,000.

"He told us he found 'the whole experience was nothing short of abuse,'" said the report, which details many other cases in which customers faced baffling bills and "abysmal" customer service.

One Ottawa man was charged $11,000 when his meter was changed and Hydro One rebilled him for five years of electricity he had already paid for.

In Waterloo, a man with terminal cancer who received no bills between July 2013 and March 2014 was "stunned to find that he owed Hydro One more than $10,000," the report said. "The company agreed to provide him with a discount, but began threatening him with disconnection at the same time."

A Sudbury man got a bill in April 2014 for $19,152 "after a long period of estimated bills." His meter had been replaced in November 2013 and it took four months to update the system. "When the actual readings from his meter arrived, the system then mistakenly charged him many multiples of what he owed. Once the error was corrected, his bill was reduced to $74," the report said.

Concerns reported to the ombudsman's office ranged from under billing and over billing to bad estimates and improper withdrawals, among other issues. The report made 66 recommendations — 65 for Hydro One, which have all been accepted, and one for the Ministry of Energy, which has not been accepted.

Customers viewed as a 'nuisance'

Marin told Solomon on CBC's Power & Politics there was a "corrupt culture" at Hydro One in which customers were "a nuisance."

Carmine Marcello, the president and CEO of Hydro One, said the company has acknowledged there were many problems and is making progress in implementing recommendations for change.

CEO on Hydro One’s progress in serving customers 8:45

He said the company has "fixed the machine," but still needs to "fix some of the cultural issues" and do a better job treating customers who have problems.

Marcello said Hydro One has "an entire new customer service organization from the senior VP on down," including a replacement of the call centre customer service provider.

Marin also expressed concern Monday that a planned partial sale of Hydro One will mean a loss of the current system of oversight for Hydro One , which services 1.3 million customers and issues one million bills a month.