Harrassing me at work

This Christina keeps calling me at work at stateing that if I don't pay them $575.53 now they are going to take me to court and them I would have to pay over 5,000 when I only barrowed $200.00. She wants me to fax here a coppy of my Drivers License and go get a prepaid card to pay off this amount. I asked her to e-mail me or send me a coverletter or something showing me the company where she was me from and she refused. I started getting suspicious when I asked her her number and she said she didn't know it and I told her that what she meant that she didn't know her number. Then she gave me a number that was no longer in service. I called it right after we hung up. so, I never faxed her the aggreement letter that she had asked me to fax over with the copies of my info. I was supposed to create a letter stateing about our agreement on me making payment plans. I went out to get a prepaid card but when I was faxing the information all my fax confirmation was telling poor line condition. She later on called me back to ask me about the fax and I told her that why did she give me a non working number and she said that her phonelines where down then I told her that if her phones are not working that maens her fax is not working and them she told me that they where and how bad I want to resolve this matter. then she said that they are going to charge me with 1. fraud 2. stealing money 3. for using a bank account that doesn't exist. what should I do? That bank account still exist but, I been going through some hardships that I have not paid what I owe. and I am just accumulating over draft fees because PDLNOW.COM PAYDAYLOAN keeps trying to take out the 200.00 plus 79.00 for other decrease it says.