I cancelled the appointment of Xiamen Traditional Chinese Medicine Hospital three times, and now I can't make an appointment by phone. Is there any way to remedy it?

If you cancel in advance, it will not affect your appointment registration. Only after making an appointment will it be blacklisted by the hospital, which will affect the registration.

In this case, I suggest you see if you can register online. If not, it means that the hospital has blacklisted you. I suggest you go to the hospital to explain the situation and apply for unsealing.