The Federal Trade Commission is reportedly looking into the company’s pricing policy

How do you know if the great deal you just snagged on Amazon is real?

The Federal Trade Commission is investigating whether the company uses “deceptive” pricing to make products look more discounted than they are in reality, Reuters reported last week. The FTC is reportedly investigating allegations from advocacy group Consumer Watchdog that Amazon intentionally misleads customers about price discounts on its website, Reuters reported. The FTC will also review the company following its decision to purchase Whole Foods

Democrats in Congress wrote to the FTC asking it to further review the merger and how it would affect “food deserts” — areas where people do not have access to grocery stores or fresh, healthy food. The FTC confirmed it has received a letter, but said it does not confirm the existence of investigations or comment on them. Michael Parrish Dudell, chief strategy officer at CouponFollow, said customers often don’t notice “incremental price differences,” but they add up.

A study conducted by Consumer Watchdog in March found that for 61% of Amazon AMZN, -2.48% products, the pre-discounted price or “reference price” used for comparison with the new sale price was higher than what the products had been sold for in the past 90 days. This means the amount Amazon advertises under “you save” could be inaccurate. Amazon said the prices reflect averages of prices listed by competitors and other sources.

“The study issued by Consumer Watchdog is deeply flawed, based on incomplete data and improper assumptions,” an Amazon spokeswoman told MarketWatch. “The conclusions the Consumer Watchdog group reached are flat out wrong. We validate the reference prices provided by manufacturers, vendors and sellers against actual prices recently found across Amazon and other retailers.”

Here are three ways to make sure you’re getting a discount:

• The website CamelCamelCamel tracks the history of a product’s price on Amazon and elsewhere to see whether its listed discount is accurate, and where it can be purchased for less. Users can also sign up for a free account and get alerts by email when an item drops below a certain price and when its price has hit an all-time low. CamelCamelCamel also has a Google Chrome plug-in that lets shoppers view price history in real time.

• Several major credit card issuers, including all Discover cards as well as Chase Sapphire Preferred and Chase Freedom, offer consumers refunds if they buy a product at one price and find it at a discount later. And the difference is not always slight. Discover will refund the difference up to $500 within 90 days of a purchase. Amazon used to offer a similar service, but discontinued the practice in May 2016.

• Another web-based service, Keepa, makes this process simple. The service plugs into your Chrome or Firefox web browser and shows via popup historical price drops for a product you’re currently viewing and recent deals on other products in real time. It also shows competitors prices and how likely an item is to go out of stock soon. (If you don’t want to download a plug-in, of course, an old-fashioned Google search can be just as effective.)