An extra blanket at the foot of the bed or a second application of sunscreen -- that's how credit card companies want consumers to think of return assistance programs. Not the first line of defense, but extra protection should a cardholder want to get a refund on a purchase after the retailer's return date.

American Express Return Protection, Discover Return Guarantee and MasterCard Satisfaction Guarantee are all return assistance programs, though they are not available to everyone. The card issuer decides which cards get the benefit. (Visa used to have a program called Return Protection, but it is no longer listed on the Visa website and the company did not return repeated requests for information.)

The programs sound expansive -- two of them extend the window for returns to 90 days past the purchase date; the other, to 60 days -- but lots of fine print and exclusions accompany the programs.

This is how they work: Let's say you use your card to buy a Prada blouse from a boutique that has a 30-day return policy. Then, on Day 35, you fall out of love with the blouse, which is hanging, tags affixed, unworn, in your closet. You visit the website for your card's assistance program, fill out a claim, mail the item to the card company (you pay shipping expenses) wait a week or two and voila, get a full refund for the blouse.

If only it were that easy. 

For instance, if you bought the blouse at Prada's Paris store, you may be out of luck -- AmEx stipulates that items have to be purchased in the United States, Puerto Rico or the U.S. Virgin Islands, while Discover only allows those made in the States. Say you lost the receipt and can't get a duplicate from the store. Sorry, no return. Or you wore the blouse a few times, then decided it just wasn't your style. Oops -- returned items must be unworn pr unused. You paid $600 for it. Nope: All three cards have limits on the price of the returnable items (Discover's is the highest, at $500; see table to compare the three return assistance programs).

MasterCard, for one, says its program is meant to extend, not replace, retailers' return policies. In fact, the item must have a return policy attached to it in the first place, says Chris Bond, group head of  North American markets for loyalty business solutions at Purchase, N.Y.-based MasterCard.

"What we're trying to do is add value" over using cash, Bond says. "We don't have huge usage of this program."

There might be a reason for that: The fine print for all three programs excludes lots of purchases. Items must be returned in new and workable condition.  Art objects, consumable goods, jewelry, cellphones, plants, animals and dozens of other items are not returnable. None of the programs refund shipping costs. Also, if your account is not in good standing, you may be denied this benefit.

A spokeswoman from the Consumer Financial Protection Bureau says the bureau has no comment about the programs, other than to urge customers to read the fine print.

Here, a comparison of the three programs. 

See related: Top retailers' policies about returning items without receipts, Compare credit card extended product warranties