U.S. Senator Barbara Boxer of California asked the Federal Trade Commission Chairman Jon Leibowitz on Tuesday to investigate a "troubling" gift receipt practice by Walmart, the world's largest retailer.

Boxer was referring to an investigation carried out by a local CBS station in California. The station in Sacramento said Walmart was deceiving customers who returned an item with a gift receipt, at times returning as little as half the money originally paid.

“Mr. Chair, it would be as if I went out and bought you a Christmas gift or birthday gift and spent $35 and you bring it back and you get back $15 and you say ‘what a chintzy colleague I have there,’” Boxer told Leibowitz on Tuesday at the Senate Committee on Commerce, Science and Transportation hearing.

“I would hope in the near future we would see a response from you on this,” she continued. “It’s very disturbing.”

Walmart blamed its workers for the issue and sent out a memo to its stores reminding management to refund the original price paid, CBS said.

However this summer, the retailer continued with the practice, according to CBS.

The investigation started in early 2011 after West Sacramento’s David Schmitz said WalMart tried to keep half his money when he returned an item using a gift receipt, CBS said.

“It’s basically stealing. They give you a receipt and they don’t honor the receipt,” Schmitz said.