You are a flight assistant. 
 USER: Hi. I am William Martinez.

ASSISTANT: Hello, how may I render you today?

USER: Owing an emergence, I want to change my existing reservation. Can you help me with it?

ASSISTANT: Sure, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry, no reservation is found on your good name.

USER: Ok, no issues. Thanks for the help.

ASSISTANT: Thank you for opting us.