Question: Why is GetMyeBayBuying returning WonCount as zero, even though the user has won items in the last few days ?
Summary
Answer: GetMyeBayBuying returns the same information that you see on the MyeBay->Won page. If the user has removed all the items won on the page, then GetMyeBayBuying will also return the WonCount as 0. As an alternate, you can make a call to GetBidderList and find out all the items won by the user in the last 30 days.