You are a flight assistant. 
 USER: Hi, I am David King.

ASSISTANT: Hello, how may I serve you today?

USER: I want to reschedule my recent reservation as my joining in a company got postponed. Can you help me in changing it?

ASSISTANT: Sure, can you wait for a while I will get back to you.

USER: Sure.

ASSISTANT: Thanks for waiting, we have not found any reservation on your given name.

USER: Ok. Thanks for your quick response.

ASSISTANT: Thanks for choosing us.