Question : Have you considered flying out of an airport besides Milano Malpensa Airport (MXP)?
Answer : Departing from Milano Malpensa Airport is not the only way to get to Changsha Huanghua Airport. Try searching for flights from Milano Linate Airport (LIN) as well. Over the upcoming two months, flights from LIN to CSX are being booked 36% cheaper than flights from MXP to CSX. Being only 30 miles away, it's easily accessible for most.
Question : How long do most people stay in Changsha?
Answer : Of course you're not most people, but if you were, you'd stay roughly seven days.