This is the only thing I do not like about A3. They almost never bend the rules, even for A3 Golds. On multiple occasions when flying LH and LX as an A3 *G, I was able to change to earlier flights without any fees as long as there were seats available. This has now become harder with their Light fares but an agent in a good mood might still do it. My 'best' example is from almost a year ago at EWR. I had a ticket EWR-FRA-BER, flying on UA/LH ticketed by LH. I arrived at EWR just as a direct EWR-BER flight was boarding. I went to the gate immediately, politely asked to get on that flight and two minutes later, no questions asked, I was in a seat on that plane. Meanwhile, Aegean won’t even change their own elites on A3 tickets to an earlier intra-Greece flight as seen from your case.