Product: Debt collection

On XX/XX/2018, my father who is XXXX yrs old came to my home holding a piece of paper. He said that he had just received a phone call from a man named XXXX XXXX, a civil servant. Looking for me because I am being sued in a big lawsuit in Civil Court. He left the telephone number ( XXXX. ) My dad asked this person how he got my fathers phone number. The man said it had just come across his fax machine. My dad came to my home immediately, holding out the paper worried that i was in trouble. I called the number asking for XXXX XXXX. I was put on hold and upon returning the female stated that there was no one with thatname there but if i would hold she would help me and she asked my name. She put me on hold and upon returning she stated that i needed to listen to her entire presentation before asking any info. She began to read information that her company had received that i owed Wells Fargo Bank {$600.00} + ( I dont remember the exact amount. ) And she rambeled on some more and ended with a total of more then {$2000.00}. SHE THEN ASKED ME HOw I PLANNED to pay for the amount. I stopped her right then and told her that she needed to send me all of this in writing. I told her that i would not pay her and she said you will be summoned and hung up on me. I waited about 10 minutes and called back. The person answered the phone XXXX XXXX. I couldnt understand him so i clarified it several times. I informed him that i needed to speak with someone about the previous phone call. XXXX came on the phone and i informed her that because the man who called my dad had said i was being sued and because the first female i spoke to had said " fine then you will get a summons, '' and hung up on me that i felt thretened. 
She started to argue and then apologized for the others behavior. I told XXXX my name and she looked up my info. I said i wanted this info in writing. She said that they didnt have to provide me anything because they had sent it to a po box i had 20 years ago and another i did not recognize. She then said i would be summoned to court. I asked where her company was located and she said XXXX, TX. I asked how m i would be summoned and she said at home or work. The phone call ended. 
I thought about the phone call for a couple days and wondered how they could serve me at home bbn or work when apparently they didnt have my address as was indicated when XXXX had said they had sent previous information to a very old address. So, on XX/XX/2018, i called the number back. A message came on saying that it was a XXXX call of some sort and i never got to speak to anyone. I called several more times and never spoke to anyone. 
This is my concern. I did have a Wells Fargo acct. 8 or 9 years ago but none of my credit reports refect any problems. Also i have a couple XXXX XXXX rdports with no indication of problems. ALSO, Wells Fargo had been invoved in opening fraudulent accounts. I do not want this to go any further. I dont even know if its real. How do i know if they have served me by mail and ive never received a summons. I do not want this to be slipped by me some how. I do not owe this debt. I do not want these people ruining my credit. WHAT DO I do?