Product: Debt collection

I was contacted at the end of last week XXXX to XXXX times a day from a collection company. The call was from a number I did n't recognize, so I was letting it go to voicemail, but the caller never left a voicemail. Today they called again several times. The number was an XXXX area code, and I had just been to XXXX for a XXXX, so I thought it might be the hospital, so I called the number calling me back. It was a debt collector, and they initiated the call by stating that I had to verify information about myself before they could tell me who they were or what debt they were calling about. They wanted me to verify my date of birth, social security number, address and email address. I was told I had to verify at least tow from that selection before they could tell me anything. I refused and said that they needed to tell me the name of their company and what company they were calling about before giving over personal information. 
They said that it was against they law, they would be breaking the law by giving their information before they got my information. I still wanted to know who they were, but they refused, and said they would just continue to call and harass until I gave up information. They said they had the last XXXX of my social, all I had to do was give them the rest of the numbers to verify. I asked them to tell me the last XXXX, but they refused saying ti was against the law for them to give it that information to me. I argued some more with a couple of different people on the phone and felt like I the conversation was going in circles, but I was in pain from my XXXX, and I wanted to figure out why they were calling so that I could get off the phone. I finally gave them my address and email address, but not more senaitive information. After that they told me that they were National Credit Adjusters, and that they were collecting on an internet payday loan. I asked who the company was, but they would n't say. At this point, my XXXX hurt from my XXXX, and I was getting annoyed by the refusal to give basic information and their attitude toward me for simply asking for verification of their information. I was arguing with them, and asked where their office was, so that I could just go there to see any paperwork proof and settle everything in person. They said good luck coming to their office, because they were in XXXX. I asked how were they in XXXX with an XXXX area code, which is the area code for XXXX XXXX. They just reiterated that they were in XXXX and gave me their address. 
I told them that whatever internet payday loan they are calling me about ( they still would n't tell me the name of the company ) was void in my state and could n't be collected on, as I had received help XXXX years ago with an internet payday loan from an organization in my state that told me they were void. I asked them why should I give them any information, because they could be a scammer, because they are trying to collect on a void loan. They said they are legitimate, and that I could look them up online, which I did, and that they have every right to collect, and was I trying to avoid my obligations. They again said that they needed my social security number, and they even gave me my date of birth and the last XXXX of my social, but they said they needed to verify the full social with me. I refused, and asked to speak to a supervisor, but she also just echoed that they need to verify my information. I ended the call by saying it was a void loan and that I should n't have to verify anything else, and then I hung up.