You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I will help you in change of flight ticket reservation.

USER: Thank you.

ASSISTANT: May I know your name please?

USER: Sure, my name is Brenda Anderson.

ASSISTANT: Please wait.

USER: Sure, I will wait.

ASSISTANT: Thanks for waiting.

USER: It's my pleasure.

ASSISTANT: Sorry I could not find your flight reservation to change it.

USER: Ok, not an issue.

ASSISTANT: Thank you.

USER: Anyways, thank you for your service.