Complaint Review: US NATIONAL FEDERAL GRANTS

I've had three calls in the last twenty-four hours from a person or persons stating they were calling from Washington,DC to give me grant money. I told her I would not give out my banking information.  She then told me I could go to Walmart to pick up my money. They spoke with very heavy accent, probably Indian.  On the first call a female hung up when I said I couldn't understand her.  The, David, insisted I had to call the account administrater back immediately with my information.  He repeated the phone number and my ID number and made sure I could repeat it back to him.

I called the number.   The man who answered stated I could go to any store, Walmart, CVS, etc. and buy a Green Dot credit card.  Then I was to put $300 dollar on card.  He stated that my card would be loaded with &7,800 within a short time.  Therefore, I would receive $7,800 free money sent by Western Union to use anyway I wanted.  I was having a difficult time understanding because of the heavy accent.  I asked to speak to someone who was American so that I could understand what he said.  He got extremely offensive.  I told him it sounded like a scam and that I might report him.  He said I could report him but I wouldn't get my money.  He then hung up.