Please help me out,is this a scam?

A lady chatted me via Facebook and she told me she would like to support my education, and she told me that, she would send me a money,5000$ to a customer care service and gave me a serial number , and she told me to call them.I called but they confirmed that I have received 5000$ but they were demanding for money (300gh) to change the money to Ghana currency.So is that a scam. please help me out.