You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Christopher Perez.

ASSISTANT: How may I serve you today?

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

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: There is no existing reservation found on your name for the modification.

USER: Not an issue. Thank you for your kind response.

ASSISTANT: Thank you for reaching us.