Portfolio Recovery Services calls me repeatedly. I have asked on several occasions that they only contact me by mail, yet they still keep calling. More than XXXX caller has been aggressive and threatening. Some callers are evasive about telling me what company they are calling from and why. Every time they call I say that I have requested to only be contacted by mail and I have been told " apparently that did n't work '' and " you 're in a lot of trouble '' etc. I do n't recall receiving anything from them in the mail so I do n't know what debt they are calling about and I do n't trust them. After the way that I have been treated by some of their collection agents, I do not feel comfortable sending them any money. They are clearly not a professional outfit and I can not trust anything they say unless I have it in writing beforehand.