got a disconnected call when answered

I answered the phone and it was a recording telling me that "tax season is almost over.....push 2....you need to push 2...." I dialed 0 and a man  named Dennis answered the phone.  I asked him to remove my number.  I gave him the number and he tells me that he is looking for "some name".  He tries to get more info by asking me if I know her or if she is at this number.  I told him don't worry about it...just remove the number.  So far so good!!! No more calls.

I missed many calls from this number and just received an ominous "call us back immediately; we will be settling this matter by the end of business today" recording. I received calls for weeks before finally calling them back. They then asked for someone else related to me with a different last name claiming she identified this number as hers with their "client." I know this to be a lie. They then tried to get me to tell them her actual phone number which I refused. I asked for the name of their "client" so I could have her call them and correct the error they have. The person on the phone refused because the "client" was confidential and having turned the matter over to them will no longer speak to the person in question.
I answered their calls on two different occasions in the same week. The first time I told them not to call this number again and the second time told them that what they are claiming is impossible but if they gave me the name of the "client" the matter would be resolved. They refused. They also tried to claim that the number was given to their "client" several years ago. I flat out told her she was lying since I've only had the phone about a year. She then said I would not be contacted again and hung up on me. I will report this number the next time I see it on my phone.

I called this number after missing several calls from it. A person with a foreign accent said he could not tell me who they were, unless I gave him my phone number first. I explained that I was going to report them and wanted to know who was calling me and he hung up on me?