You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: Will you please help me in changing my reservation as my plan to go for trekking got postponed?

ASSISTANT: Sure. May I know your name?

USER: I am Gregory Thomas.

ASSISTANT: Give me a minute.

USER: Sure.

ASSISTANT: Thanks for being waiting, We didn't found any reservation by this name.

USER: Ok fine, thanks for your assistance.

ASSISTANT: Thank you for reaching us.