If you car has been on the docks for a month there are a few possible excuses:
1) Your car has swine flu, or loaded with cocaine, and has been pinged by customs
2) The workshop forgot to apply for import approval and they're still waiting on it
3) If you are paying your importer rather than the suppliers direct, your importer has run out of money and they won't release the car off the docks until the bills are paid.
Regardless of the reason, make sure you're not having to pay the storage fees.