You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you at this moment?

USER: I am planning to change an existing reservation, due to health issue. Can you please help me out?

ASSISTANT: Sure, I am here to help you with this.

USER: Thank you.

ASSISTANT: Can you please provide your name to check your reservation status?

USER: My name is Jack Roberts.

ASSISTANT: Jack Roberts, there is no active reservation found under your name in our database.

USER: That's fine, thank you for your help.

ASSISTANT: Thank you for contacting us.