Product: Debt collection

On XX/XX/XXXX at XXXX I received a call from XXXX a man that said he had some documents that had been forwarded to his office regarding some legal matters. When I asked him the name of the company he was with he said XXXX, XXXX XXXX XXXX, he said he wanted to know if I was going to be around Friday to give me some papers. I asked him Are you intending to serve me?, he replied hesitantly something like that, but listen call this number XXXX and tell them my name they can give me more information I called XXXX and another man answered, said that he could provide me with the information needed if I can verify that XXXX was the last 4 of my social. I did not want to verify that information I just said OK. He proceeded to tell me I owed money on a payday loan, ( which is a fact, however they sold my account to XXXX XXXX XXXX not XXXX or XXXX ) he told me I had to make payments of {$120.00} every month to keep my account from going to legal. I was caught off guard and told him I needed time to figure my budget out, he told me that I needed to talk to him by Friday or else my account will be forwarded. He then proceeded to ask me if I got any certified letters, I told him no. he verified my address, and I told him I never got anything. He then proceeded to verify my email address and I confirmed he told me he was going to email me some information on the payment plan and to look out for it. So I waited to see if an email ever came and nothing came. 

XX/XX/XXXX at XXXX I got a voicemail from XXXX stating : This message is for XXXX this is XXXX, regarding some paperwork I just received in my office yesterday. Your information as I stated in my prior message I do have a request I have sign for a notice of intent regarding a pending case thats been filed against you. I havent heard from you I just wanted to confirm my schedule for service I will be stopping by if you could please make yourself available between XXXX and if you could please have a valid ID if claimant their number is XXXX is your case number XXXX. 

First- there was no prior message, nor do I think its okay for them to threaten to show up anywhere. Especially my home after I verified my address the day before. 
Instead of calling the XXXX number, I called the local number that left me the voicemail and I asked them what documents they keep talking about, they told me they couldnt discuss anything unless I give them the last 4 of my social, keep in mind they blurted out the day before, and I would not. He told me that they already sent it out and to hold as they needed to go over my account. the man stated they sent me my information to my email address. I asked why nothing was mailed and he said it was, when I asked what was mailed he said the mail I asked what mail a statement, a notice, a legal document what??? he became frustrated told me not to yell and that this was a legal matter and that he couldnt discuss much of anything else. 
I dont have any recording devices so I had another party nearby to hear what they were saying and be a witness to the madness. 

Although I know this is illegal it still makes me scared that someone has my social, my address, email address and personal information at disposal to them.