You should start by investigating with your state to determine whether or not the collection agency is even licensed to collect debts in your state. Also, read this article.

They can't seek a driver's license suspension unless they get a judgment, so an 'investigation' is not enough. As for whether they could seek a suspension even with a judgment, I doubt it based on the facts you've provided, but you haven't told us the state in which the accident occurred. I am assuming that you have not been sued over the accident, and no judgment has been entered against you -- if that's not the case, please share the details.