This happened to me once, and the seeds never arrived. I had insurance, so the bank re-sent the order. I've had several good experiences with european banks, but hate the customs hurdle. I'm going to try to find some US companies in the future. I've got a small test order with one right now.
I also have a small test order, no insurance, with Seedsman (placed Jul 7), which hasn't arrived yet. I have high hopes for CA based Grower's Choice, and placed an order with them yesterday. If time is of the essence, I'd place another order with a different company.
The lost order was from herbies, placed Nov 11 2016. After the package had been in chicago customs for 10 days, I contacted herbies. They sent a new package that arrived Dec 5. Their literature had said to wait until Dec 5 to contact about lost package, but I jumped the gun a bit.
Wait a little longer i have had orders sit in isc for over 5 days then start moving again still took 6 days after it started moving again...