Canadian grocery giant Loblaw is blaming old labels for customer confusion over prices on items advertised with bright red stickers that promote a "GREAT BUY."

On Wednesday, a regular customer of Atlantic Superstore filed a complaint with Canada's Competition Bureau over price discrepancies she's noticed where the advertised "GREAT BUY" costs more than the old price underneath it.

"I got concerned because it's not just a matter of one store and they're off on their management one day," says Lorraine Martin, who lives in Shubenacadie, N.S.

"That can happen. But when I see it in a couple of different stores in the same chain, then I get nervous."

A spokesman for Superstore's parent company, Loblaw Companies Ltd., said Thursday that prices routinely rise and drop depending on "promotions or various business reasons."

"With these changes, sometimes new price labels are placed over old ones," Mark Boudreau, Loblaw's Atlantic director of corporate affairs, told CBC News. He adds the company understands a customer's confusion "when they pulled back the current prices and saw lower, older prices."

Boudreau said the company's own review found old labels dating back to 2014 covered by new price labels.

"We will use this situation to review this practice with our stores," he said.

Martin usually shops at either the Elmsdale or Truro Superstore and says she likes the PC Rewards program and special alerts she receives about sales.

She keeps a close eye on savings being advertised and has noticed some items with red labels marked "GREAT BUYS," may not be that great after all.

At the Elmsdale Superstore on Tuesday, she found Glad medium zipper bags (30 bags per box) labelled a "GREAT BUY," with two or more costing $2.50 each and a single box selling for $4.99. Under the "GREAT BUY" sticker was an older price of $2.99, a difference of $2 for anyone buying just one box.

While this is a 'GREAT BUY' for customers who purchase two or more, they will pay $2 more than the price underneath. (Lorraine Martin)

Martin spotted several similar situations where the "GREAT BUY" price for one item was more than its original price.

For example, she found Pergamano parchment paper with a "GREAT BUY" sticker price of $3.59. The original sticker price under the label was $3.49.

At two stores, the checkout price for the parchment paper was $3.59, but at another store, on Joseph Howe Drive in Halifax, the checkout price was the original $3.49.

This 'GREAT BUY' on parchment paper is 10 cents more than the price underneath. (Yvonne Colbert/CBC)

"The first few times I noticed it I thought, 'OK, that's human error,' I mean that happens," Martin said. "The people working in the store are always interrupted for directions and different things in the store."

The first time she noticed a price discrepancy she went to customer service. The store gave her the product for free.

She was initially satisfied, but then noticed the same pricing issues at other Superstore locations.

Trust shaken

"Sometimes I only have an hour in between my kids's games to go and run my errands," she said. "A lot of my friends have their little kids in the cart and they don't have the time to check every single price.

"So you want to have that trust and comfort because a grocery store is somewhere where you want to go in, grab things you need so you can get going in your everyday life."

On Tuesday, CBC News visited Superstores in Elmsdale, Bayers Lake and on Joseph Howe Drive in Halifax and found price discrepancies.

At the Joseph Howe location, PC BM reduced mint chip ice cream was labelled a "GREAT BUY" for $3.99. The original price underneath was $3.49.

This 'GREAT BUY' on ice cream will cost a customer 50 cents more than the price underneath. (Yvonne Colbert/CBC)

"It's maybe a few cents here and a few cents there, but in a chain that size, I question what does that mean for everybody else," Martin said.

"Because if I caught it once, and then I told it to a few of my friends and they watch now and they caught it quite a few times, what does that mean for the rest of Atlantic Canadians and Canadians?"

Investigation

Price-related representations are regulated by Canada's Competition Act, which is enforced by the Competition Bureau. Spokesman Phil Norris would not comment on Martin's case.

"The Competition Bureau has an obligation to conduct a thorough review of the facts and examination of the evidence prior to drawing any conclusions as to whether or not there has been a violation of the Competition Act," he said in an email.

Loblaw spokesman Mark Boudreau told CBC News that investigating the situation is a priority as the company tries to figure out why this happened.