Sen. Barbara Boxer wants the Federal Trade Commission to investigate whether Walmart is giving consumers as much as it should when they use gift receipts to return items.
The California Democrats says she should know soon whether the FTC will take a look.
A probe by CBS stations KOVR in Sacramento and KYW in Philadelphia found that Walmart customers returning items using gift receipts weren't always getting back the full amount originally paid for the items.
KOVR investigative reporter Kurtis Ming filled "Early Show" viewers in last week on the stations' work, which used hidden cameras.
In some cases, the refunds were much less than the original prices.
CBS News spent $106.85 at Walmart, but the gift receipts returned $62.32. The total loss was $44.53.
Sally Greenberg, executive director of the National Consumers League, told CBS News, "I think it's reprehensible. ... Consumers are cynical enough about company policy. This just adds to their sense of mistrust and disappointment."
The retail giant blamed the problem on confusion among some of its cashiers, resulting in their not following company policy.
Lorenzo Lopez, a Walmart spokesperson, provided CBS News with a video statement in which he says, "It's our expectation to refund the original purchase price when returning an item with a gift receipt."
Following the investigation, Walmart says, it issued a memo to its more than 3,800 stores nationwide to make sure all employees know that consumers with gift receipts should receive a full refund for the original amount paid.
It's also worth noting -- not all store items have the same return policies. So, Ming added, "You've got to be clear on the rules before you buy that next gift."