You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I want to change my existing reservation, can you please help me to book a flight?

ASSISTANT: Sure, may I know your name?

USER: I am Pamela Campbell.

ASSISTANT: Sorry, there is no reservation found under your name?

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your time.

ASSISTANT: Welcome.