I had a similar problem with a Priority package 
in the US... it seemed that the only way for them 
to actually put in some effort to find it was to 
file the insurance claim.  Then they will 
actually look for it so they don't have to pay 
out the money.  They did find the package I sent, 
although it took about seven months -_-.  Of 
course, I don't know how that would work with 
international, becuase with the Priority, the 
person who was supposed to recieve the item had 
to file the claim.