Perhaps you’ll find the answer you’re looking for here:
How can I ask for a credit to be converted to cash?
If you have a credit over €4 you can request a cash equivalent directly from italo.it. If you have a Borsellino Italo you can make your request simply by logging into your Italo account and clicking on My Page. To redeem a compensation voucher or an Italo credit, go to the Self Service area, which you will find by clicking on Support and scrolling down.