Dear Cathy
 To begin, my advice is that you do not deliver the original receipt, until it are by means of a Public Notary or authorized authority (Court) that gives faith of the delivery, and by means of one against receipt with certified copy.
 In addition I think that you should in contact with the American Embassy or the Consulate, for legal assistance in order that you present a denounce against them  in the Ministerio Público (Attorney Public Office), for the crime of threats and those who prove (Probably fraud).