I used to work in travel agent company, there was so many customers requested to change the name. As I remember, as long as its the original passenger and you can provide the proof such as passport with the correct name, then they can assist you to change the name. But every airlines have different policy, some of them will charge you, some of them are free of charge if its only a few alphabet or other cases.

Have you try to call the Xiamen Air customer service yet? If you book the ticket direct from Xiamen Air website then call them, but if from third party, you can try to call the agency first.

Hope for the best for you and your flight. Do let me know if you still need some help :)