An elderly Ontario woman is demanding a hefty refund from Bell Canada after learning she’s been double billed for almost 12 years.

Bell has been pulling about $133 a month from the bank account of Margaret Belean, 83 of Brantford, Ont., for a second phone line which she doesn’t actually have, according to her son, John Vekemans.

He estimates the overcharging adds up to about $18,000.

The problem is “definitely at [Bell’s] end of the game,” Vekemans told CBC News. “But they keep telling me it’s a bank error and [the bank] keeps telling me it’s Bell. So I'm bouncing back and forth between RBC and Bell and getting nowhere.”

The error went unnoticed because Belean’s bills are paid automatically through her bank and she said she hasn’t paid close enough attention to what is being taken out of her account.

But she wants the money back.

“It’s my money that I would like to have back,” she said.

Her son said he's been chasing Bell for a couple of months for a refund.

Bell told CBC News it has looked into the claim and admits someone at the company made a mistake many years ago — linking Belean’s bank account with a telephone number belonging to a business.

“We'll certainly make good to Mrs. Belean, and are now in the process of pulling old records to determine the amounts involved,” Bell said in a statement.

It hopes to refund the money in the next couple of weeks.

Belean said she no longer assumes the bills coming off her account are accurate.