You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Nicole Collins.

ASSISTANT: How may I guide you today?

USER: Can you help me for changing my existing reservation?

ASSISTANT: Sure, I will help you with that. Please wait for a minute.

USER: Thank you.

ASSISTANT: I am sorry to say that there is no reservation found.

USER: Oh! It's ok no problem, thank you for your services.

ASSISTANT: Thank you for  contacting us.