Turkish Airlines Ticket Date Change Issue

I purchased a ticket from Turkish Airlines on February 27th for my son who is serving in the military in Cyprus. However, due to a mandatory change in his departure time, we needed to change the ticket date. They refused to make the change, claiming 'no available tickets' and charged a ₺600 fee. We submitted feedback but received a negative response, citing 'it's in the contract.' I understand they might be right, but how can a soldier, who has limited access to phone and internet in a place where it's hard to get even weekly access, read and agree to the contract? I would expect a large institution like this to make some exceptions for soldiers. It's unfortunate, and I truly feel sorry for the soldier. I just wanted to express my frustration. Have a good day.