waka network.com Called me to say that i had taken a survey and won a $100 walmart gift card and $60 gas card internet, Michigan

I was contacted by phone by a person who said I did a online survey about walmart , which i did a long  time ago and that i won a walmart $100 gift card and a $60 gas card.  They gave me the whole line about walmart etc.  They asked for a $2.99 processing fee which i gave them a check number to use.  They never sent me the gas card or walmart card.  I called them several times with no results.  This is a big scam and they are making a big amount  money from people who are Walmart customers  by using the Walmart name.