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: Sure, I will help you. Can I have your name?

USER: Dennis Walker here.

ASSISTANT: Please, hold on a moment.

USER: Sure.

ASSISTANT: Thank you for waiting, I did not find any reservation on your name to change.

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

ASSISTANT: Thank you for approaching us.