OP is very lucky that I9 changed her ticket for only $200. Under the contract she agreed to with I9, she was not due any refund or reimbursement:

"The passenger must hold the necessary travelling documents and comply with laws, regulations, orders, requirements and conditions issued by the home, destination and transit countries, and therefore, he will have no right for refund or reimbursement from the Carrier"

This is a fairly common provision in most carriers' contracts. It would have done OP no good had I9 boarded her only to have her refused admission to Italy and returned to the US on the next flight. Not to mention that I9 would have been fined and had to transport OP and that OP would have been responsible for those.

It is always 100% the passenger's obligation to assure that all documents are in order. Sounds harsh, but that is it.