Government Grants and Teasury David or Martin Wanted me to use Western Union, gift card , credid card, or bank to send them money to get my money WashingtonDC Dist of Columbia

Received a call from David stating I had been choosen to receive a $8, 200 grant. He stated that the grant amount was actually $8, 350 but I had to have it sent to me via Western Union, or my crerdit card, to get it that day (Wed., Sept. 28 or , 2016) and that I would then have to put it in a Federal bank and  I also had to buy three iTune gift cards totalling $150 dollars to complete the transaction. I asked them to just send the check to me via US Mail and was told they could not do that, but had to have it deposited directly into my checking account, sent via Western Union, or put on my credit card.  I received a call from Martin telling me that my credit rating was to low to receive the grant. I told Martin that it was not low accordibg to FICA, and that my credit rating was actually good. 

David called back and told me that Martin was his manager and that he had me confusedd with someone else. I told him I did not need the brant money that same day and was willing to wait until next week. He asked for the name of my bank along with the routing and account numbers. He wanted to withdraw $350.00 to cover the cost of having the money transfered  from one bank to another. He called again and told me my bank would not let him withdraw the money. He againwanted me to buy iTune gift cards and use Western Union.  I told him I was not not going to pay $350.00 to get a grant from the government. He told me he would take the money out of his pocket. Agfter approximately four hours of playing phone tag, I ended the call due to having to get dressed and go to a class at 5:00 pm.