You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I oblige you today?

USER: I am Sandra Thompson here. I need to change my existing reservation, which is done recently. Can you please help me out?

ASSISTANT: Sure, please wait.

USER: Thank you for considering my request., I will wait for your positive response.

ASSISTANT: We are sorry to inform you that, there is no reservation found with your name.

USER: Not a problem, thank you for the information.

ASSISTANT: You are welcome.