Credit reporting / collections question?

So I am trying to buy a new car only to find out that my 700 credit score is now a 640 because there is some $8 past due owed to some collection agency I have never heard of, or heard from. It may be a mistake but assuming it is not what can I do? I feel like it is insane that 8 dollars can throw your credit score off by 60 points, and the fact that no one ever contacted me about a past due amount for 8 dollars leads me to believe maybe I can have my credit amended. Anyone with any insight and advice to give would be greatly appreciated thanks!