Who is liable for items missing from a shipped package?

I think the 9 day delay between when they got your package and when they let you know that the item was missing is very suspicious.  You might end up having to sue them, to get your money back, and if it comes to that, this fact is very important.

Many times, the two (or more) sides to a lawsuit will have very different versions of the facts.  When you have hard evidence that fits in better with your version than anyone else's, you need to emphasize that, because it's a very strong argument for the court to believe your version more.