Thanks for the advice. I am gold but the ticket was economy.

In the meantime, I have read EU261/2004 and, although there is no compensation possible if the flight is beyond 14 days, but the airline must offer re-routing and if there is no such offer I am entitled to "reimbursement of the price difference with the new ticket (under comparable transport conditions)". So it seems that there is recourse but I'd rather have the airline play nice and not involve buying my own ticket and a lengthy EU261/2004 dispute and a possible regulator involvement, especially since I would like to collect 4 flight segments on Aegean. It's a pity that Aegean cannot be more consumer friendly. I guess the "best midsize airline" title does not mean anything anymore.