Walmart shopper? (inside)

(CBS News)

The beauty of a gift receipt is that you can give a present without a price tag and the gift can still be returned.

But when you use a gift receipt, how do you know you're getting the right amount back?

An investigation by CBS stations CBS-13 in Sacramento and CBS-3 in Philadelphia found that Walmart's gift receipts don't always return your money's worth.

CBS-13 investigative reporter Kurtis Ming shared the story on "The Early Show."

Ming said team went to Walmart storesy, purchased items, and asked for a gift receipt. But time after time, when they returned those items using the gift receipt, they got back much less than what was originally paid.

And the investigative teams aren't the only customers affected.

David Schmitz used a gift receipt to return a present he bought at a Walmart in California.

Schmitz told CBS News, "When I purchased the item it cost $15 plus tax. When I tried to return the item using the gift receipt, I was offered $7.50 plus tax."

The makeup kit Schmitz purchased had since gone on sale, so he was only offered back the reduced price -- not what he originally paid.

Schmitz said, "It seemed very obvious that a person should be getting the full amount, and that's the purpose of a receipt."

The Walmart eventually gave Schmitz a full refund, but Ming said the CBS News teams wanted to test Walmart's policy.

So, with hidden cameras rolling, they visited stores in California and New Jersey, purchased items and returned them with gift receipts after the items had gone on sale.

An electric blanket cost a CBS team $31.03 at a New Jersey Walmart, but when it was returned, they received $20.33 back.

On a hidden camera tape, a member of the CBS News team said, "I thought it was more than that?"

The Walmart associate replies, "It probably was, but if you don't have a receipt with the actual price, I have to give you whatever comes up."

The team originally paid $14 for a pair of boots and a t-shirt. The return? Just $10.

When asked why it was $10 instead of $14, the Walmart associate says, "It doesn't tell us the price, whatever scans in is what you get."

CBS News spent $106.85 at Walmart, but the gift receipts returned $62.32. The total loss was $44.53.

Sarah 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."

Walmart says the employees seen in the CBS News investigation weren't following company policy. Lorenzo Lopez, a Walmart spokesperson, provided CBS News with a video statement. In it, Lopez, said, "It's our expectation to refund the original purchase price when returning an item with a gift receipt."

But Schmitz isn't buying Walmart's explanation -- or any more items with a gift receipt from its stores.

Schmitz said, "It was set up to where the person giving would not know if the gift was returned and the person receiving the gift would not know the amount paid."

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, under company policy. 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."