You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Stephen Clark here.

ASSISTANT: How can I assist you Stephen Clark?

USER: Can you please help me in changing my reservation? as my planned program has been postponed.

ASSISTANT: Sure, I will help you with this. There is no active reservation found under your name in our database.

USER: May be something went wrong while reserving my ticket. That's ok, thank you for your information.

ASSISTANT: Thank you for contacting us.