You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello,. How may I address you?

USER: I just want to change an existing reservation due to my tournament got post pone.

ASSISTANT: Sure, may I know your name?

USER: I am William Thompson.

ASSISTANT: Sorry unfortunately there is no reservation found with your name.

USER: Ok.

ASSISTANT: Thank you.

USER: Thanks for your assistance.