No one likes to get a call from a debt collector, but it’s especially tough to deal with one for a debt you don’t think you owe.

A former gym member recently posted a question to Reddit about her debt-collection pickle with her former gym. The woman canceled her gym membership, but the owner claimed she needed to continue paying, and he sent those unpaid bills to a debt collector. She argued about her contract having ended, and when the gym sent her a copy of it, showing she was in a yearlong membership agreement. Here’s the thing: She signed that contract well over a year ago, and she said the date was clearly altered to make it appear otherwise.

With the altered contract, it looked like she owed membership dues, which is pretty much all the proof a collector needs to pursue the account. Mark Schiffman, vice president of public affairs for ACA International, said the creditor is responsible for making sure the account is legitimate, so it’s up to the consumer to prove it isn’t.

If you’re contacted by a debt collector, one of your first action items should be to make sure the debt is valid. Whatever your question, the collector will likely go back to the creditor with which you supposedly incurred the debt to set things straight. Of course, if you’re having issues with the creditor, rather than the collector, the validation process isn’t going to help you much, but here are some tips for proving a debt isn’t yours.

“In the debt collection transaction the consumer has every right to ask for verification of a debt and the ability to dispute it,” Schiffman said via email. “To the extent they can, consumers should save relevant documentation on their own in the event they need it in the future (e.g., cancellation confirmation, credit terms, correspondence with a creditor about an account/debt, etc.)”

In the case of the consumer arguing with the owner of her former gym, she may want to consult a legal professional in her attempt to get the collections attempts to end.

What’s the Harm?

She has a good reason for wanting that off her plate: Collection accounts have a negative effect on credit standing, so she may be unfairly denied access to credit or lower interest rates if she doesn’t dispute the account. As far as getting collectors off her case, she can write a cease-and-desist letter. People dealing with collectors should know their basic rights, like when a collector can contact you and how they can treat you.

Disputed accounts aren’t factored into credit scores, but if you’re going through the process of trying to get something removed from your credit report, you’ll want to carefully monitor your credit so you know how the account is affecting you. Regularly checking your credit score will allow you to identify any problems on your credit report (like a collection account you didn’t know about), and it’s generally a good habit to form if you want to maintain good financial health. You can review your credit data for free through Credit.com and take advantage of personalized, expert tips for improving and maintaining your credit standing. You may also want to pull copies of your credit reports, which you can do for free once a year.