Does any body know the contact of U.S custom of SAN FRANCISCO

We have an express mail from China, which inbound to SAN FRANCISCO one week ago, and it's still there by online check today. We contacted with USPS many times, but every time we were told there's nothing more but waiting. We are thinking to contact directly with the U.S custom at SAN FRANCISCO, but we have nowhere to check the contacts, such as telephone, fax or mail. Please do us a favour if you happen to know this, and we appreicate if you can give us your comments or suggestion on how to handle such a situation.

Many thanks and have a great weekend.