Looking at the Italotreno site for another option from Roma Termini to Florence SMN. Will defintely take a fast train and have not bought tickets from Trentalia because I do not know how long it will take me to get from FCO Airport (customs. etc). My understanding is that Trentalia does not refund, but the Italotreno says this for a flex fare.
"Flex
You can make free of charge unlimited changes to your travel time/date and passenger’s name up to 3 minutes prior to departure time, for as many times you like.
If you cancel, you get a 80% refund. If you miss your train, you have 2 hours of “extra time” to find a seat on the next train asking to the in station Italo Staff or in Italo Ticket Office or calling Italo Assistenza at +39 06 89371892 (subject to availability)"
Has anyone used Italotreno and been able to make a change ?