You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I need to change my reservation as my plan to go for trekking got postponed. Can you help me?

ASSISTANT: Sure. Can I know your name?

USER: I am Robert Martinez.

ASSISTANT: Ok. Let me check details with your recent reservation.

USER: Sure, take your own time.

ASSISTANT: Sorry, there is no reservation by name Robert Martinez.

USER: Ok fine, thanks for your response.

ASSISTANT: Thank you.