Call the 800 lost luggage number and ask for a supervisor. Tell them you would like them to contact SIN and you would be more then happy to wait while they do so. If nothing is accomplished, tell the supervisor that since UA had it in their possession at one time, as evidenced by the expedite tag number u have, they are now responsible for it's loss. Tell them that since they lost it, you have no choice but to file a claim against them for the value of your documents contained inside. This should at least get them moving in the right direction.