Is there any certificate called anti terrorist and airport clearance certificate?

Needed by any one traveling from any Arab nation or African nation to the United states.This is because an organization that claim they have forwarded my documents to the US Bureau of immigrant affairs are telling me to pay 1350$ to get this Certificate.I have already paid them 2585$ for the documents they claim they have processed and forwarded to the US bureau if immigrant affairs.they say the office has refused to give them the documents to mail to me through DHL and that unless i pay the bill the documents will not be mailed.