You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Susan Roberts.

ASSISTANT: How can I assist you?

USER: Can you help me for changing my existing reservation?

ASSISTANT: Sure Susan, please wait a moment.

USER: Ok, I will wait for your reply.

ASSISTANT: Sorry, there is no reservation found on your name.

USER: Oh! It's ok, no problem. Thank you for your services.

ASSISTANT: Thank you for approaching us.