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

ASSISTANT: Hello. How may I help you?

USER: As I am suffering from health issues I want to change my existing reservation can you help me with that?

ASSISTANT: Sure, wait for a minute.

USER: Ok.

ASSISTANT: Sorry, Melissa no reservation found on your name.

USER: Thank you for the quick response.

ASSISTANT: Thank you for approaching us.