Tui, outbound delay was due to late arrival of previous flight, inbound was due to a damaged window on the plane flying from UK to Crete, which we would be flying back on.
I did argue the points with them, but after several weeks of emails I was getting nowhere.
Haven't flown with Tui since, so there loss.
Neither of those events are extraordinary circumstances. You should contact a solicitor to fight that for you as that excuse is generic and expected as part of the process. They expect you to say "oh ok then" and not pursue it.