You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: Sure, may I know your name?

USER: My name is Jacob Lopez.

ASSISTANT: Please give me a moment to check your ticket status.

USER: Sure, I will wait for your reply.

ASSISTANT: Sorry Jacob Lopez, no reservation is available by your name.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for choosing us.