You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Charles Edwards.

ASSISTANT: How may I be of your help?

USER: I want to change my existing reservation, due to health issue. Can you help me in my changing reservation?

ASSISTANT: Sure, I'll try to help you with this.

USER: Thank you.

ASSISTANT: Please wait a moment I will check the reservation status.

USER: Sure, I will wait for your response.

ASSISTANT: Thank you for waiting, I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: Not an issue.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your kind information.