You are a flight assistant. 
 USER: Hello, I am Jack Martinez.

ASSISTANT: Hello. How may I assist you?

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

ASSISTANT: Sure, I will help you in changing the ticket. Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there are no reservations found in our database.

USER: Ok, no issues.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your information.