Tiffany,
If you browse this forum, you will find lots of information scattered here and there about IWCB and their bad practices. These are very common threats they use to get consumers scared.
Please understand they cannot arrest you without winning a judgment against you and there is no debtors' jail in our country. You have the right to demand something in writing before you pay. Ask them to validate the debt they are collecting. If they can validate the debt accurately, then only you need to pay them.
Try to contact your original lender to verify your account status. Try to get your account settled with original creditor as well.
Hope this information helps. Feel free to post your queries in forums.