Some Manitoba Hydro customers are getting hit with inaccurate, super-high charges this month — including one woman who got a $700 bill — and the Crown corporation says it's not entirely sure why.

Jennifer Doran says her hydro bill is usually around $150. When she opened her envelope this month and saw it was $700, she thought it was "a little outrageous."

"This is actually our first summer in this house. I was expecting higher because of the air conditioning, but not $700 higher," she said, laughing.

A phone call to Hydro confirmed it was an error and the bill was adjusted based on her meter reading the following day, down to $170.

"It'll make me a little more diligent about checking my meters, for sure," she said.

Corporation asks affected customers to call in

Anthonie Koop, a spokesperson for Manitoba Hydro, said Doran isn't the only customer who's gotten a much higher bill than normal. The corporation started noticing mistakes in bills around July 13, but it can't be sure how many people have been hit by the error.

Officials suspect the problem may lie in a glitch in the bill estimating system being caused by higher-than-normal temperatures this summer, but Koop said that's not certain yet.

"We're not really sure what's going on, to be quite honest, and so we're not really sure how many people are being affected," he said. "And [we] won't know that until the meter reading is done this month for the next billing cycle."

The mistakes appear to be popping up in bills that are being estimated this month, he said, and will be corrected with adjusted bills next month when those people's meters are read.

In the meantime, the corporation is asking anybody with unexpected, significant increases in their bills to call and let them know.

"Call our contact centre," he said. "We'll take that meter reading and adjust their bill accordingly."

If you get a wonky bill, you can contact Manitoba Hydro in Winnipeg at 204-480-5900. If you live outside the city, call their toll-free line at 1-888-624-9376.