I received a voice message from a person calling herself XXXX XXXX stating that she was from a collection agency and she needed to speak to me. When I called back, the same day, she stated that I had an outstanding balance and she had been trying to contact me. She was very aggressive on the call, she raised her voice and over me for the majority of the phone call, she refused to send me anything in the mail ( stating that I was not in a position to tell her how to do her job ), and she stated that she tried to leave me voicemails but could not because my inbox was full, which is completely untrue. The phone call was so upsetting that I was shaking at the end of it. I had no idea what debt she was speaking about as I assumed that I had completed payment of my son 's medical bills in XXXX of 2014. I was able to speak the debtor, XXXX and found that there was XXXX unpaid bill and XXXX duplicate charge. At this time I have no choice but to work with XXXX XXXX because I do not have any documentation from Wakefield and Associates stating what I supposedly owe. I am also not inclined to call them and repeat the same type of aggressive situation again. It is my understanding the the collection agency must send documentation and they must not intimidate. I feel that Wakefield and Associates, specifically XXXX XXXX, are in violation of these regulations. I believe a recording of this conversation was recorded because there was a message at the beginning of my call that stated all calls are recorded.