You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I serve you today?

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, may I know your name?

USER: Sure, my name is Richard Thompson.

ASSISTANT: Ok, please wait for a minute.

USER: Sure, I will wait.

ASSISTANT: Sorry, there is no reservation found on your name to change.

USER: Ok, no problem. Anyways, thank you for your service.

ASSISTANT: Thank you for reaching us.