Some donors to Donald Trump’s presidential campaign recently discovered that it’s difficult to cancel recurring monthly donations on the campaign’s website.

A CNN reporter tweeted an email he received detailing one donor’s frustrations about trying to cancel the payments in early August.

Subsequently, the news website Mic did an investigation comparing the process of canceling donations to Trump and Hillary Clinton’s campaigns. When donors signed up to make monthly donations to Clinton’s campaign, the confirmation email they received included a separate email address they could use to ask questions about their donation; Trump’s confirmation email did not include such an address.

Clinton’s campaign website also included a prominently-placed button for removing a credit card (to stop the recurring payments); it was unclear on Trump’s website how to remove a credit card, Mic concluded. The site also found that removing a card from Trump’s site required a few additional steps, including clicking on a small gray question mark, which directed a user to a separate page in order to “manage” a donation to Trump’s campaign. From there, it’s possible to cancel a monthly payment.

Trump’s campaign, which didn’t respond to MarketWatch’s request for comment, isn’t the only entity making recurring charges difficult to cancel. In fact, now that it’s common for consumers to set up automatic credit card payments for bills and subscription services, they’re increasingly finding unwanted charges on their bills.

The startup Handy, which allows consumers to sign up for home-cleaning services, was the subject of an episode of the podcast “Reply All” in 2015 because of the difficulty a consumer had canceling the service. (Handy now has clear instructions on its site about how to cancel).

Fabletics, the company actress Kate Hudson co-founded, which is owned by retail company JustFab and manufactures athletic clothing, has faced similar complaints about being difficult to cancel. In response, the company has since changed some of its practices. ”Customers who accidentally sign up for membership are costly to the business, so we do everything we can to avoid that from happening,” said a Fabletics spokesman in an email. He said it should be obvious to consumers based on the Fabletics website that they are signing up for a subscription service.

Consumers have also had complaints about Adore Me, a lingerie subscription service; they didn’t realize that they were automatically enrolling for the company’s VIP program, which involves a nearly $40 monthly fee. It was also difficult for them to cancel their subscriptions, according to the Better Business Bureau (BBB), a nonprofit based in Arlington, Virginia, that rates companies and charities according to quality and how closely they adhere to BBB’s standards. Adore Me is in the process of making improvements to its website, a spokeswoman said in an email, with the goal of making sure customers can see they have a choice between the VIP program and paying as they go. Customers can also now unsubscribe from the service and request refunds on the company’s website, rather than having to call or send an email.

The BBB lists requirements for subscriptions and automatic shipments in its Code of Advertising. Sites should have opt-in features for recurring payments that are “prominently disclosed and explained.” They must also be easy to cancel, and their terms shouldn’t be buried in fine print, the code states.

Consumers can file complaints with the BBB; if the bureau sees a pattern with the complaints, it will bring the issue up with the company at fault. If the company doesn’t fix the issue, a BBB spokeswoman said in an email, they may end up with an “F” rating with the BBB, which may also escalate the issue to the Federal Trade Commission (FTC).

The FTC files complaints with relevant courts on behalf of consumers who feel they have been duped by companies, including those with “deceptive offers” online.

JustFab and Fabletics are now accredited with the BBB after addressing previous complaints; Fabletics has an “A-” rating. Handy Technologies Inc., known as Handy, is not yet accredited, according to the BBB’s website and has a rating of “B-”. Adore Me is not accredited with the BBB and has a rating of “D+.”

What to do if you find an unwanted charge

It’s a good idea to keep a spreadsheet or other list of every recurring payment one has, said Matt Schulz, a senior industry analyst at the credit-card website CreditCards.com.

It may also be smart to set up online or calendar alerts when subscriptions or short-term promotions are set to end, so that consumers can unsubscribe during the correct time frame.

But if a consumer discovers unwanted charges even after attempting to cancel a service, it’s best to take the complaint to the credit-card issuer, which can handle the dispute for the consumer, including potentially refunding previous charges, Schulz said.

He recommended letting an issuer know about the unwanted charge as soon as possible.

Consumers should issue a written complaint to their issuers within 60 days after a charge has appeared on a credit-card statement in order to have full legal rights to dispute the charge, according to the Fair Credit Billing Act.

That written letter should include the consumer’s name and account number, describe the error that occurred (including the type of error, the date it happened and the amount) and why the consumer believes there was an error, according to a spokesman for the Consumer Financial Protection Bureau.

The FTC has an online sample of a letter consumers can use to dispute a charge.

If a consumer does this, the company that charged him or her must resolve the complaint within two complete billing cycles; that process must not take longer than 90 days, according to the Fair Credit Billing Act.

While the card issuer investigates the dispute, the consumer does not have to pay the disputed charge, and the card issuer can’t charge interest on that amount.

Several credit-card issuers include information about how to dispute charges on their websites, including American Express AXP, -5.09% , Discover DFS, -6.79% and Citi C, -2.07% .

It can be helpful to take notes during the process of trying to cancel a subscription or dispute a charge, including the names of customer-service representatives consumers encounter during that process, Schulz said. “The better records you keep, the better off you’ll be in getting things handled,” he said.