You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I am Helen Williams, want to alter my reservation dates. Can you please help me?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure, take your time.

ASSISTANT: Sorry we did not find any reservation with your name.

USER: It's ok, thank you.

ASSISTANT: Thank you for reaching us.