TORONTO - Ontario's ombudsman says Hydro One has been threatening to cut off the electricity of customers who are behind on payments, even during the winter months.

Andre Marin says Hydro One's own policy is to not disconnect customers during the winter, but he says the utility told him that telling customers they'll do so is a common tactic in the industry to get people to pay.

Marin has been looking into Hydro One billing for 13 months and says the number of complaints he has received recently passed 10,000 -- the highest total for any of his investigations to date.

His full report will be issued in the spring, but he says so far several themes have emerged, including incorrect bills, large "estimated" bills and unexpectedly large payments withdrawn from customers' bank accounts.

Marin highlighted one case involving a Sudbury-area man who opened his monthly statement to find a $19,000 bill -- which was ultimately reduced to just $74.

Hydro One did not immediately respond to a request for comment.