It probably has been blown up already...
If you read his full message, he wrote that they have it at the front desk, which probably means they are not concerned of a bomb threat from it.
What I would tell you if you have no luck getting it back with anyone. Ask them to ship it to you and pay them via credit card. Its another option to try.
Hatzlacha Rabbah and wish you the best on getting it back to you soon.