Credit report error

Mercedes Benz has mistakenly billed me for a vehicle I never purchased. I’ve been diligently trying to resolve the situation with Mercedes Benz Financial in order to close the loan associated with the car I returned, but they have not taken any action.

To make matters worse, they have reported this issue to credit reporting agencies, resulting in a significant drop of 53 points in both my and my wife’s credit scores. Could you kindly assist me with this matter?