You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Yes, can you tell your name?

USER: Samantha Johnson here.

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

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.