See if it has been reported on your credit. If it has, then you can open a dispute with all 3 credit bureaus online.

Once you register the dispute, the company that reported it MUST provide documentation to you and to the reporting agencies that the debt is a) yours and b) legit.

If they fail to do so within 90 days, the item is removed from your report.

Credit Report Dispute: Correct Errors in Your Credit File

TransUnion Personal: Credit Disputes – Submit a Dispute, Check Dispute Status and Understand the Credit Dispute Process.

Dispute Credit Report information at Experian.com

Good luck and stick with it.