ITA scheduled 2 months ago my flight to Vietnam from Barcelona via Rome and Paris with only 20 minutes for the connection in Paris. This was due to a schedule change on the Rome to Paris leg.

Paris to Vietnam leg was with Vietnam Airlines codeshare. Ticket is entirely ITA.

I discussed it with them at the time and they did not cancel my flights and suggested there were multiple passengers on the flight so the flight to Vietnam would wait and we would be chaparoned through security and immigration.

I spoke with them yesterday and no issues on the flight but I was unable to select seats on the Paris to Vietnam leg.

I called again today to double check and I was told I had a missed connection and they could not re-route me with any other airline. They also (not consistently as I spoke to several different people) said that the Paris to Vietnam flight was cancelled as well. (Vietnam airlines website still has the flight flying)

I had not received any email or notifcation of issues since the original schedule change.

I phoned up and asked for a refund which has been provided but I still have not received an email confirming cancellation and they pivot to "missing connection" rather than it being outright cancelled which is the effect and why they refunded.

How should I go about claiming EU 261 given this?

Thanks