Demand a refund and return the rifle back to him, You should also report the situation to GB.
How did you read the post and come up with this as a response? I guess I am assuming that you mean "demand a refund" from the seller on GB?
It's pretty clear that the most likely circumstance, by far, is that the FFL's junior goon boy that was told to sign in the rifle; threw the bolt away. Why should the seller be responsible for that? It's not like someone wants a r700 bolt without the corresponding action. This response, if I read it correctly is nearly as ridiculous as some of the ones on the "What do I do now" thread.
To the OP, sorry for your luck, but it appears that two gurus are stepping up big again to get you squared away!