Cars can be built, but not complete. If certain parts are not available as a car goes down the line, you don't stop the whole line - you just let it continue to the end of the line, where obviously it doesn't get the final sign off. It goes instead to an area that the company I worked for called "after rectification", which was a sort of black hole because there are no automatic status updates issued while a car is sat in what is effectively a large car park. Saying that, the Certificate of Conformity should not be issued until the car has been signed off as complete - otherwise it doesn't conform!
I have no idea whether any of this applies to the OP's order.
I have no idea whether any of this applies to the OP's order.