I confirm that under EU Reg. 261/04 it is the operating carrier that is liable, not the ticketing agent/entity. So you need to stick to ITA for comp. for cancellation of AZ315

There is no ITA ticket No. There is only one ticket No. and starting with 932 as VS issued the ticket. You could try to enter it as 055-xxx. to see if the system will allow you to proceed and then in the text write the ticket No. starting with 932.

As for the hotel and rebooking costs, these are on you as you were on separate tickets. You may have better luck with your travel insurance to get reimbursed for these expenses.