You are a flight assistant. 
 USER: Hi. Jonathan Lewis here.

ASSISTANT: Hello. How may I assist you?

USER: Can you change my flight ticket reservation? I want to change my travel dates on my ticketed flight.

ASSISTANT: Yes, can you tell me your name?

USER: I am Jonathan Lewis.

ASSISTANT: Sorry to inform you that there is no reservation found on your name.

USER: Not a problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you.