You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I want to change my existing reservation which is done recently due to some health issues, can you please help me in this?

ASSISTANT: Sure, I will help you with that. May I know your good name?

USER: Sure, my name is Patrick Williams.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Thank you for waiting, sorry there is no reservation found on your name to change it.

USER: Ok, no problem.

ASSISTANT: Thank you for visiting us.

USER: Anyways, thank you for your appreciable service.