Yes it appears that I have almost accepted the flight change, but the flights are now out of sequence completely, so someone should be able to see the inconsistency in the flight pairings.

I'll call them again this morning to see if there's a supervisor to speak with.

Also, FYI...... On the outbound sectors, they did make changes to my departures times so we agreed to fly 2 days earlier than planned. When we got to the airport, we were not allowed to check in. It was because SV had accepted our flight change, but didn't not re-issue tickets properly. The reservation had new flights, but no ticket numbers attached.

I am very fortunate to have the correct travel insurance to fall back on, so for anyone reading this - if you fly with a non-EU carrier, you may have little or no rights at all to bring a claim. SV are not budging one bit.