You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Steven Lee on this end.

ASSISTANT: How may I guide you today?

USER: I would like to make few changes in my existing reservation due to my office work, can you help me?

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

USER: Thank you for your positive response. Sure.

ASSISTANT: Steven Lee, I am sorry to say that there is no reservation found under your details.

USER: Oh! That's sad to know, thank you for checking anyways.

ASSISTANT: Thank you for reaching us.

USER: You are most welcome.