Act like you are with the news, be like:
Good evening, this is Anderson Cooper from CNN, we are calling this number on behalf of all Americans who are called and scammed out of their life savings, are you aware that you are a suspect of felony charges?
I must tell you that you are on National television live as we speak. I have my assistant typing transcripts as we speak. The Cable News Network has filed a class-action lawsuit against _________ for felony telephone fraud and racketeering, the federal government has permission to seize, RICO, and confiscate items that may be used in the court of law. We recommend you not disconnect or hang up this call, destruction of evidence is a felony called spoliation, and by hanging up you are deleting the letter of intent I am telling you verbally.