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?

ASSISTANT: Sure, I will help you. Can you please tell me your name?

USER: Sure, my name is Janet Campbell.

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

USER: Ok, no problem. I will try with another booking agency.

ASSISTANT: Thank you for choosing us.

USER: Anyways, thank you for your service.