They told me I had a outstanding debt since 2008 and If I don't pay 5,000 dollars by Tuesday Dec.27th I will be served court papers and have a nice day.

Opening move by a phony debt scammer.  They want to make you think you owe money on some bogus loan you never took out.  There is no filing, no warrant for your arrest.  No one coming to you home of job with "papers".
They will lie and threaten, they may call your work numbers, family and friends.  These are real crooks.
    Do NOT call back or interact with these crooks.   They will just keep calling and making threats.  The language they use is pure bs, and is supposed to sound scary and legal.  Hang Tough.  For now, ignore and block the calls, check this link and have a plan.
http://800notes.com/arts/harassing-calls-from ... ou-need-to-know