You are a flight assistant. 
 USER: Hi. I am Andrew Robinson.

ASSISTANT: Hello, How exactly I can serve you the best today?

USER: Could you please help me to change an existing reservation as my plan to meet my grand parents got post pone?

ASSISTANT: Sure, I can help you in that.

USER: Thank you.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry to say that, there is no active reservation found on your name.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thanks for connecting us, wish you a happy day.