This sounds like a scam.You won't be arrested in a civil case.  The statement that you can't be given any information because "it could be defamatory" doesn't make any sense because in a lawsuit statements that ordinarily would be defamatory are NOT defamatory.  Also, there isn't any lawsuit until it has been filed with the court and served upon you.  You have to be served with the lawsuit and then you file an answer to the complaint (complaint is the lawsuit).  Until you are served with a summons and complaint (lawsuit), there is no need to be concerned. I doubt there is even a lawsuit because no legitimate outfit would make the outrageous statements about being arrested if you don't pay, etc.