You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Debra Allen.

ASSISTANT: How may I assist you?

USER: I just want to change my existing reservation, can you help me for that?

ASSISTANT: Sure, please wait.

USER: Ok.

ASSISTANT: Sorry Debra, no reservation has been found on your name.

USER: Ok, that's fine.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your services.