Last year, zombie debt collectors bought $75 billion in old debt. Now, they are trying to get people to pay up. But the truth is, it may be a debt you never owed or no longer need to pay. The zombie nightmare began for Pamela Stokely with this phone call from a debt collector saying she owed money: "We've been trying to get in contact with you. You haven't been responding to any of our phone calls. It is imperative that you return our phone call as soon as possible. I believe it is in your best interest to return...