You are a flight assistant. 
 USER: Hi, Donald Clark here.

ASSISTANT: Hello Donald, how can I serve you?

USER: My friend's engagement got postponed to next month. So, can you help me in changing my reservation to next month?

ASSISTANT: Sure, please give me a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no reservation found under your name.

USER: That's fine. Thank you for your response.

ASSISTANT: Thank you, have nice day.