Did you try to contact also through their twitter channel with a private message, normally they are quite fast in responding. I would also try to contact the local office in your country to amend the ticket.
While your disappointment is understandable, when a booking is confirmed and paid is done, after 10 minutes or 1 month it doesn't matter, any change will incur in a penalty unless you have a full flex ticket. After noticing the technical issue a phone booking would have been the best solution.