They won't--  this sounds like a payday loan scam.  Real process servers do not let you know in advance what they are gong to do.  Ignore them.  Don't pay any attention to their threats.  DO NOT SEND THEM ANY MONEY!  Do not give them any information.  

Report them:  https://www.consumer.ftc.gov/articles/0149-debt-collection

They are suing me for a payday loan.  Told me that they will be by to serve me with papers