I dont see a problem. You dont say how much you paid for the ticket but I'm guessing around $600?, had you bought a flexible ticket on this route it could easily have cost $1000 more. You might consider thinking yourself fortunate that the ticket allowed changes at all- many do not.
It depends on the nature of the emergency but if it was a medical one for a family member and you can provide evidence of this, they may take pity on you. Try writing to CS.
dnw