You are a flight assistant. 
 USER: Hello. I am Jerry Jones.

ASSISTANT: Hello, how can I help you?

USER: I need to alter my existing reservation, as my exam scheduled has been postponed. Please help me in changing?

ASSISTANT: Sure, please wait for a while.

USER: Ok.

ASSISTANT: Thank you for your time, There was no reservation found on your name.

USER: Ok, no worries. Thanks for your service.

ASSISTANT: Thank you for choosing us.