Capital Management Services, LP wrong name on claim and refused to provide general info Buffalo, New York

My mother received a letter from CMS stating that she owed $686 to Citibank (South Dakota). First of all the letter on the claim was incorrect, only the last name matched my mother's name, and my mother has never had an account with Citibank. I called CMS and they immediately asked me for my mother's date of birth and social security number. We refused to provide such information over the phone and the operator became very rude. I told them that I only wanted general inormation regarding procedures becasue my intentions were just to write a letter clarifying that my mother was not the responsible party listed on the letter, and I only wanted to confirm if a letter would be appropriate. They refused to answer my questions. The operator told me that she would not give me any info at all unless I provided the info requested and hung up. I called again and asked to speak to a Manager. The manager was not helpful either.  I explained that I only wanted general procedural information as to how I could reply to this claim so my mother's confidential information or anybodies confidential information should not be a factor. The manager refused to provide any guidance; all she stated was "do what ever you want to do". I don't understand why they cannot provide any general information regarding their procedures or guidance as to how to resolve the claim without having to provide confidential information over the phone to a company that we have not had a business with.