You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you today?

USER: I want to change my reservation due to my health issues, can you please help me with this?

ASSISTANT: Sure, may I know your good name?

USER: I am Alexander Williams.

ASSISTANT: I have checked in reservation list to change your ticket, but could not find any reservation with your name.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.