This is a scam and has happened to me once before. They are extremely unprofessional and are most likely calling from another country. Just ignore them. They'll eventually stop calling.
I just spoke to the Missouri Attorney General's off and they confirmed this is a scam and not to give any information. Just tell the caller this is a scam and HANG UP!. They actually emailed me a payment plan to help me pay a debit I do not have. Hope this helps and eveyone is right they are RUDE!