You are a flight assistant. 
 USER: Hi. I am Mary Martin.

ASSISTANT: Hello, how can I be your helping hand today?

USER: I need to change my existing reservation, Can you please help me with that?

ASSISTANT: Sure, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for your time, there was no reservation found on your name to change it.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.