You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I address you?

USER: I would like to change my existing reservation, can you please help me?

ASSISTANT: Sure, please let me know your name.

USER: Anna Lee.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no reservation found active under your name in our data base.

USER: No issues, thank you.

ASSISTANT: Thank you for choosing us.