I need some advice. I did some off-turk work for a requester about 10 days ago. I had done a hit for him here and he asked if I was interested in more of the same work. I said yes, because they'd already paid me. I did the work, submitted it and got an email about 4 days later from him asking for an invoice from paypal. Paypal was being weird and wouldn't send the invoice, so I sent a requester for the money. Nothing happened in 2 days so I sent another email and he replied saying he didn't get a request and to send him a PDF invoice. I did that and today I get an email from someone else claiming they work for the requester, saying they need a W-9 to pay me. What do I do?