To dispute the charge, file a claim with the credit bureau that you found the car loan on. This is typically TransUnion, Experian, or Equifax. You usually can do this online. However, you may want to call to file the dispute to get more information regarding the charge.
The good news is that most credit report disputes are investigated and solved within 30 days. If you notice that it’s taking longer than that, you may want to contact the credit bureau again to see if there’s anything you can do to facilitate a faster process. Hopefully, it’s a clerical error and not identity theft.