You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Shirley Davis.

ASSISTANT: How may I assist you?

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

ASSISTANT: Ok, please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Thanks for your time, there is a flight reserved with your name.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome.