You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I serve you today?

USER: Due to health issues, I want to change my existing reservation. can you help me with it?

ASSISTANT: Sure, may I know your good name?

USER: My name is Patrick Taylor.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Thanks for waiting, sorry to say that, no reservation was found with your name.

USER: Ok, no issues.

ASSISTANT: Thanks for choosing us.

USER: Thanks for the help.