You're on social media or surfing the web when you see an ad for a free trial of a new wrinkle cream or diet pill. It may be endorsed by a celebrity and all you have to pay is a small fee for shipping and handling. But that free trial may be anything but free.

The Better Business Bureau released a new report Wednesday on what it calls "subscription traps and deceptive free trials." It says these schemes have hurt millions worldwide.

"I come across these sorts of ads, not trying to look for them, on almost a daily basis," said Steve Baker, author of the report, who is an international investigation specialist at the BBB, in a phone interview with CNBC. "These things have just permeated the internet at this point."

Free trials are also on the radar of the Federal Trade Commission, which has brought actions against companies in this sector.

"Think of free trial offers as a hook. And they are a hook to get consumer credit card information," said Janet Evans, a lawyer with the FTC's Bureau of Consumer Protection. "Consumers lose money and we get a lot of complaints on them."

The BBB identified 36,986 complaints over the last three years, though not all involve monetary loss. The average amount lost was $186, according to the group's report.

The schemes often start with an ad for a free product or with an article that seems to appear on a news site, according to the BBB.

"If you can locate and read the fine print on the order page, or the terms and conditions buried by a link, you'll discover that you may have only 14 days to receive, evaluate and return the product to avoid being charged $100 or more. In addition, the same hidden information may state that by accepting the offer, you've also signed up for monthly shipments of the products. Those also will be charged to your credit card and become subscription traps. Many people find it difficult to contact the seller to stop recurring charges, halt shipments and get a refund," the report said.

Not all free trials have issues. "Free trial offers can be legitimate ways to introduce new products. Credible companies make sure consumers understand what they are signing up for and do not hide key information," the report said.

One way the companies convince people to buy the products are with celebrity endorsements, which Baker told CNBC were an important factor. However, according to the BBB most of these endorsements are fake.

"Some celebrities come forward and complained because they have not authorized use," Baker said.

In some instances, companies will disclose in fine print that the endorsements are not real. Baker said it took him 10 minutes to find one such disclosure.

Once people make the first payment, they are often signing up for a monthly subscription without realizing it. At that point, opting out can be a challenge.

"Most free trial offer companies have telephone numbers to call, although many victims report to BBB that they have difficulty in getting a live person on the phone, and that many of those answering the calls can be quite rude. For the most part victims report that they are often able to stop future shipments and charges, but usually cannot get refunds for charges already made. At best victims are offered partial refunds," the BBB said.

Under the Restore Online Shopper's Confidence Act, companies must clearly lay out the terms of free trials or other subscriptions before consumers give their credit card information. Companies are also required to have express consumer permission before charging consumers and they must have a simple mechanism for the consumer to stop the recurring charges, according to the FTC's Evans.

Even if you charge on a credit card, you may still have trouble getting your money back.

"Unfortunately, credit card companies or, more accurately, payment card networks, have often been reluctant to provide refunds to victims of free trial offers or subscription traps," the report said. Of 1,000 victims of free trial scams, only 57 percent filed for a chargeback with their credit card company, according to the BBB. Of those, 44 percent did not get a chargeback and 14 percent got a partial refund.

The American Bankers Association said it supports the work of consumer protection officials.

"Card companies frequently intervene to ensure that consumers are reimbursed for unauthorized transactions and for transactions where a merchant violates payment network rules. These rules are more stringent than the law and provide additional safeguards to consumers," said Nessa Feddis, senior vice president, deputy chief counsel, consumer protection and payments at the ABA, in a statement sent to CNBC. "Even with these protections, card companies may not always be able to intervene in cases where the customer has authorized the payment and the merchant has delivered a product as agreed. That is why it is so important to be careful about buying from people or companies you don't know."

American Express has "procedures in place to ensure Card Members are not held liable for fraudulent or unauthorized charges," it said in a statement to CNBC. "We do monitor our network for fraudulent, deceptive and unfair practices relating to the sale, advertising, promotion or distribution of goods or services to consumers. We look at a number of factors, such as frequent consumer complaints, regulatory or consumer advocate inquiries, and high levels of disputed charges and/or chargebacks. We will review the merchant and take the appropriate action, up to terminating the relationship."

Discover recommends customers first attempt to work out the situation with the merchant as they say it can be the fastest path to resolution.

"If the customer is unsuccessful in resolving the situation with a merchant, they can also engage us, and we will work with Discover Network to investigate the matter," the company said in a statement to CNBC.



"After final resolution of the investigation, including review of any additional information from the customer and responses from the merchant, if we determine the customer's dispute to be valid, then those transaction(s) will be permanently reversed. … Discover Network monitors merchants to ensure they are not operating or accepting cards in connection with sale of any goods or services using deceptive or predatory practices and/or in violation of any applicable laws."

Mastercard changed its rules for free trials and subscriptions starting next year. "Mastercard is taking steps to ensure cardholders have a simple and safe experience when purchasing goods and services from merchants offering free trials or subscriptions," the company said in a statement sent to CNBC.

"To increase transparency, after the trial period has ended, but before any additional payments are made by the cardholder, the merchant must provide the cardholder with the transaction amount, the payment date, the merchant name as well as instructions for cancelling a transaction. Finally, the merchant must send a receipt to the cardholder for each transaction by email or text message with instructions on how to cancel the service."

Visa did not respond to CNBC's request for comment.

This is not the only issue with the subscription industry.

A CNBC investigation last month found that some online subscription companies employ confusing business tactics, such as opting customers in to recurring charges without their knowledge and making it very difficult for shoppers to opt out of the monthly fees.

Apple, eHarmony and other companies have paid millions in settlements to resolve class-action lawsuits alleging that they were automatically renewing subscriptions without consumer consent.

A class-action lawsuit against Apple, which settled for $16.5 million in November, accused the company of charging customer accounts through in-app subscriptions without their knowledge. Popular online dating website eHarmony settled a similar class action in January 2018 for more than $1.3 million with an additional $1 million in restitution for similar claims.

The companies deny any wrongdoing. Both suits claimed the companies violated California's automatic renewal law, which requires retailers to "clearly and conspicuously disclose" any recurring charges, and to receive "affirmative consent" from the consumer.

A top Federal Trade Commission official told CNBC that the agency is closely monitoring online subscription services.